Delivery of medical devices

ABSTRACT

A stent delivery system can include a core member, an introducer sheath, and a microcatheter. The core member can have a first section and a second section distal to the first section. The second section can have a bending stiffness per unit length that is less than a bending stiffness per unit length of the first section. The introducer sheath can have a lumen configured to receive the core member therethrough. The introducer sheath can have a length of at least about 80 cm. The microcatheter can have a lumen and a proximal end configured to interface with a distal end of the introducer sheath for delivering the core member into the microcatheter lumen.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.14/040,477, filed Sep. 27, 2013, which claims the benefit of U.S.Provisional Patent Application No. 61/870,755, filed Aug. 27, 2013. Theentirety of each of these applications is incorporated herein byreference.

BACKGROUND

Walls of the vasculature, particularly arterial walls, may develop areasof pathological dilatation called aneurysms. As is well known, aneurysmshave thin, weak walls that are prone to rupturing. Aneurysms can be theresult of the vessel wall being weakened by disease, injury, or acongenital abnormality. Aneurysms could be found in different parts ofthe body, and the most common are abdominal aortic aneurysms and brainor cerebral aneurysms in the neurovasculature. When the weakened wall ofan aneurysm ruptures, it can result in death, especially if it is acerebral aneurysm that ruptures.

Aneurysms are generally treated by excluding the weakened part of thevessel from the arterial circulation. For treating a cerebral aneurysm,such reinforcement is done in many ways including: (i) surgicalclipping, where a metal clip is secured around the base of the aneurysm;(ii) packing the aneurysm with small, flexible wire coils (micro-coils);(iii) using embolic materials to “fill” an aneurysm; (iv) usingdetachable balloons or coils to occlude the parent vessel that suppliesthe aneurysm; and (v) intravascular stenting.

Intravascular stents are well known in the medical arts for thetreatment of vascular stenoses or aneurysms. Stents are prostheses thatexpand radially or otherwise within a vessel or lumen to provide supportagainst the collapse of the vessel. Methods for delivering theseintravascular stents are also well known.

In conventional methods of introducing a compressed stent into a vesseland positioning it within in an area of stenosis or an aneurysm, aguiding catheter having a distal tip is percutaneously introduced intothe vascular system of a patient. The guiding catheter is advancedwithin the vessel until its distal tip is proximate the stenosis oraneurysm. A guidewire positioned within an inner lumen of a second,inner catheter and the inner catheter are advanced through the distalend of the guiding catheter. The guidewire is then advanced out of thedistal end of the guiding catheter into the vessel until the distalportion of the guidewire carrying the compressed stent is positioned atthe point of the lesion within the vessel. Once the compressed stent islocated at the lesion, the stent may be released and expanded so that itsupports the vessel.

SUMMARY

At least one aspect of the disclosure provides methods and apparatusesfor delivering an occluding device or devices (e.g., stent or stents) inthe body. The occluding device can easily conform to the shape of thetortuous vessels of the vasculature. The occluding device can be used ina variety of applications. For example, in some embodiments, theoccluding device can direct the blood flow within a vessel away from ananeurysm. Additionally, such an occluding device can allow adequateblood flow to be provided to adjacent structures such that thosestructures, whether they are branch vessels or oxygen demanding tissues,are not deprived of the necessary blood flow.

The delivery of an intravascular stent to a treatment site within thevessel of a patient requires substantial precision. Generally, duringthe implantation process, a stent is passed through a vessel to atreatment location. The stent can be expanded at the treatment location,often by allowing a first end of the stent to expand and thereafterslowly expanding the remainder of the stent until the entire stent hasbeen expanded. The process of initially contacting the vessel wall asthe first end of the stent expands can be referred to as “landing” thestent. The final position of the stent within the vessel is generallydetermined by its initial placement or landing within the vessel. Insome situations, the stent may initially be “landed” in a suboptimallocation within the vessel. Using traditional methods and apparatuses,it may be very difficult for a clinician to reposition the stent withinthe vessel. For example, a clinician may be unable to recapture,collapse, withdraw, or resheath the stent back into the catheter afterthe stent has been partially expanded within the vessel. As such, theinitial landing is critical to successful placement of the stent.

The subject technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the subjecttechnology are described as numbered embodiments (1, 2, 3, etc.) forconvenience. These are provided as examples and do not limit the subjecttechnology. It is noted that any of the dependent embodiments may becombined in any combination with each other or one or more otherindependent embodiments, to form an independent embodiment. The otherembodiments can be presented in a similar manner. The following is anon-limiting summary of some embodiments presented herein:

Embodiment 1. A stent delivery system, comprising:

-   -   a core member having an intermediate portion and an elongate,        spiral-cut tube extending proximally of the intermediate        portion, the tube having first and second flex zones, the second        flex zone being proximal of the first flex zone, and a        transition zone between the first and second flex zones;    -   the first flex zone having a bending stiffness of less than 12        N*mmA2 so as to be navigable through the internal carotid artery        bifurcation, the spiral cut of the tube in the first flex zone        having a first pitch;    -   the second flex zone having a bending stiffness of greater than        60 N*mm{circumflex over ( )}2, the spiral cut of the tube in the        second flex zone having a second pitch different from the first        pitch;    -   wherein the spiral cut of the tube in the transition zone        changes from the first pitch to the second pitch in a series of        pitch transitions, the spiral cut pitch in the transition zone        increasing by an overall percent increase from the first pitch        to the second pitch, such that the average overall percent        increase achieved per transition is 15% or less; and    -   a stent carried by the intermediate portion.

Embodiment 2. The system of Embodiment 1, wherein the pitch transitionsof the spiral cut of the tube have a density along the transition zonegreater than 1 transition per centimeter.

Embodiment 3. The system of Embodiment 1, wherein the pitch of thespiral cut of the tube increases by over 150% from the first pitch tothe second pitch in a proximal direction in the transition zone.

Embodiment 4. The system of Embodiment 1, wherein the first flex zonelength is greater than 60 mm.

Embodiment 5. The system of Embodiment 1, wherein the second flex zonelength is greater than 30 mm.

Embodiment 6. The system of Embodiment 1, wherein the second flex zonebending stiffness is 60-100 N*mm{circumflex over ( )}2.

Embodiment 7. The system of Embodiment 1, wherein the transition zonecomprises about 25 pitch transitions.

Embodiment 8. The system of Embodiment 1, wherein the first flex zone isnavigable to the M1 bifurcation.

Embodiment 9. The system of Embodiment 8, wherein the second flex zoneis navigable to the common carotid artery.

Embodiment 10. The system of Embodiment 1, further comprising a secondtransition zone distal of the first flex zone, the spiral cut of thetube in the second transition zone decreasing from the second pitch in asecond series of pitch transitions, the second series of pitchtransitions having a density along the second transition zone greaterthan five transitions per centimeter.

Embodiment 11. The system of Embodiment 1, wherein a distal end of thefirst flex zone is spaced 8-12 mm from a proximal end of the stent.

Embodiment 12. The system of Embodiment 11, wherein a distal end of thesecond flex zone is spaced 225-275 mm from a proximal end of the stent.

Embodiment 13. The system of Embodiment 1, wherein the spiral cut of thetube prevails along a cut length of the tube, the cut length beinggreater than 50 cm.

Embodiment 14. The system of Embodiment 13, wherein the spiral cut iscontiguous along the cut length.

Embodiment 15. The system of Embodiment 13, further comprising apolymeric outer layer disposed over the outer surface of the tube alongat least a portion of the cut length, wherein the spiral cut is not cutinto the polymeric outer layer.

Embodiment 16. The system of Embodiment 15, wherein the polymeric outerlayer covers the entire cut length of the tube.

Embodiment 17. A stent delivery system, comprising:

-   -   a core member having an intermediate portion and an elongate,        spiral-cut tube extending proximally of the intermediate        portion, the tube having an uncut-tube bending stiffness and a        first flex zone located near a distal end of the tube, and a        transition zone extending proximally from the first flex zone;    -   the first flex zone having a bending stiffness of less than 5%        of the uncut-tube bending stiffness so as to be navigable        through the carotid siphon, the spiral cut of the tube in the        first flex zone having a first pitch;    -   wherein the spiral cut of the tube in the transition zone        increases from the first pitch in a proximal direction in a        series of pitch transitions, the spiral cut pitch in the        transition zone increasing by an overall percent increase from        the first pitch, such that the average overall percent increase        achieved per transition is 15% or less; and    -   a stent carried by the intermediate portion.

Embodiment 18. The system of Embodiment 17, wherein the pitchtransitions of the spiral cut of the tube have a density along thetransition zone greater than 1 transition per centimeter.

Embodiment 19. The system of Embodiment 17, wherein the pitch of thespiral cut of the tube increases by over 150% from the first pitch in aproximal direction in the transition zone.

Embodiment 20. The system of Embodiment 17, wherein the first flex zonelength is greater than 60 mm.

Embodiment 21. The system of Embodiment 17, wherein the transition zonecomprises about 25 pitch transitions.

Embodiment 22. The system of Embodiment 17, wherein the first flex zoneis navigable to the M1 bifurcation.

Embodiment 23. The system of Embodiment 17, further comprising a secondtransition zone distal of the first flex zone, the spiral cut of thetube in the second transition zone decreasing from the second pitch in asecond series of pitch transitions, the second series of pitchtransitions having a density along the second transition zone greaterthan five transitions per centimeter.

Embodiment 24. The system of Embodiment 17, wherein a distal end of thefirst flex zone is spaced 8-12 mm from a proximal end of the stent.

Embodiment 25. The system of Embodiment 17, wherein the spiral cut ofthe tube prevails along a cut length of the tube, the cut length beinggreater than 50 cm.

Embodiment 26. The system of Embodiment 25, wherein the spiral cut iscontiguous along the cut length.

Embodiment 27. The system of Embodiment 25, further comprising apolymeric outer layer disposed over the outer surface of the tube alongat least a portion of the cut length, wherein the spiral cut is not cutinto the polymeric outer layer.

Embodiment 28. The system of Embodiment 27, wherein the polymeric outerlayer covers the entire cut length of the tube.

Embodiment 29. The system of Embodiment 17, wherein the tube has anouter diameter of 0.040″ or less, and a wall thickness of 0.010″ orless.

Embodiment 30. A stent delivery system, comprising:

-   -   a core member having an intermediate portion and an elongate,        spiral-cut tube extending proximally of the intermediate        portion, the tube having first and second flex zones, the second        flex zone being proximal of the first flex zone, and a        transition zone between the first and second flex zones;    -   the first flex zone having a bending stiffness of less than 220        N*mmA2 so as to be navigable through the aortic arch, the spiral        cut of the tube in the first flex zone having a first pitch,    -   the second flex zone having a bending stiffness of greater than        250 N*mm{circumflex over ( )}2, the spiral cut of the tube in        the second flex zone having a second pitch different from the        first pitch,    -   wherein the spiral cut of the tube in the transition zone        changes from the first pitch to the second pitch in a series of        pitch transitions, the spiral cut pitch in the transition zone        increasing by an overall percent increase from the first pitch        to the second pitch, such that the average overall percent        increase achieved per transition is 10% or less; and    -   a stent carried by the intermediate portion.

Embodiment 31. The system of Embodiment 30, wherein the pitchtransitions of the spiral cut of the tube have a density along thetransition zone greater than 1 transition per centimeter.

Embodiment 32. The system of Embodiment 30, wherein the pitch of thespiral cut of the tube increases by over 35% from the first pitch to thesecond pitch in a proximal direction in the transition zone.

Embodiment 33. The system of Embodiment 30, wherein the first flex zonelength is greater than 200 mm.

Embodiment 34. The system of Embodiment 30, wherein the second flex zonelength is greater than 30 mm.

Embodiment 35. The system of Embodiment 30, wherein the second flex zonebending stiffness is 250-310 N*mm{circumflex over ( )}2.

Embodiment 36. The system of Embodiment 30, wherein the transition zonecomprises about 8 pitch transitions.

Embodiment 37. The system of Embodiment 30, wherein a distal end of thefirst flex zone is spaced 480-540 mm from a proximal end of the stent.

Embodiment 38. The system of Embodiment 37, wherein a distal end of thesecond flex zone is spaced 780-820 mm from a proximal end of the stent.

Embodiment 39. The system of Embodiment 30, wherein the spiral cut ofthe tube prevails along a cut length of the tube, the cut length beinggreater than 50 cm.

Embodiment 40. The system of Embodiment 39, wherein the spiral cut iscontiguous along the cut length.

Embodiment 41. The system of Embodiment 39, further comprising apolymeric outer layer disposed over the outer surface of the tube alongat least a portion of the cut length, wherein the spiral cut is not cutinto the polymeric outer layer.

Embodiment 42. The system of Embodiment 41, wherein the polymeric outerlayer covers the entire cut length of the tube.

Embodiment 43. A stent delivery system, comprising:

-   -   a core member having an intermediate portion and an elongate,        spiral-cut tube extending proximally of the intermediate        portion, the tube having first and second flex zones, the second        flex zone being proximal of the first flex zone, and a        transition zone between the first and second flex zones;    -   the first flex zone having a bending stiffness of less than 120        N*mmA2 so as to be navigable to the common carotid artery, the        spiral cut of the tube in the first flex zone having a first        pitch,    -   the second flex zone having a bending stiffness of greater than        180 N*mm{circumflex over ( )}2, the spiral cut of the tube in        the second flex zone having a second pitch different from the        first pitch    -   wherein the spiral cut of the tube in the transition zone        changes from the first pitch to the second pitch in a series of        pitch transitions, the spiral cut pitch in the transition zone        increasing by an overall percent increase from the first pitch        to the second pitch, such that the average overall percent        increase achieved per transition is 10% or less; and    -   a stent carried by the intermediate portion.

Embodiment 44. The system of Embodiment 43, wherein the pitchtransitions of the spiral cut of the tube have a density along thetransition zone greater than 0.5 transitions per centimeter.

Embodiment 45. The system of Embodiment 43, wherein the pitch of thespiral cut of the tube increases by over 80% from the first pitch to thesecond pitch in a proximal direction in the transition zone.

Embodiment 46. The system of Embodiment 43, wherein the first flex zonelength is greater than 50 mm.

Embodiment 47. The system of Embodiment 43, wherein the second flex zonelength is greater than 200 mm.

Embodiment 48. The system of Embodiment 43, wherein the second flex zonebending stiffness is 190-210 N*mm{circumflex over ( )}2.

Embodiment 49. The system of Embodiment 43, wherein the transition zonecomprises about 10 pitch transitions.

Embodiment 50. The system of Embodiment 43, wherein a distal end of thefirst flex zone is spaced 300-340 mm from a proximal end of the stent.

Embodiment 51. The system of Embodiment 50, wherein a distal end of thesecond flex zone is spaced 480-540 mm from a proximal end of the stent.

Embodiment 52. The system of Embodiment 43, wherein the spiral cut ofthe tube prevails along a cut length of the tube, the cut length beinggreater than 50 cm.

Embodiment 53. The system of Embodiment 52, wherein the spiral cut iscontiguous along the cut length.

Embodiment 54. The system of Embodiment 52, further comprising apolymeric outer layer disposed over the outer surface of the tube alongat least a portion of the cut length, wherein the spiral cut is not cutinto the polymeric outer layer.

Embodiment 55. The system of Embodiment 54, wherein the polymeric outerlayer covers the entire cut length of the tube.

Embodiment 56. A stent delivery system, comprising:

-   -   a core member having an intermediate portion and an elongate,        spiral-cut tube extending proximally of the intermediate        portion, the tube having first, second, and third flex zones and        first and second transition zones, the first transition zone        between the first and second flex zones, the second transition        zone between the second and third flex zones,    -   the core member being configured such that (i) a bending        stiffness of the first flex zone is greater than a bending        stiffness of the second flex zone and a bending stiffness of the        third flex zone and (ii) the bending stiffness of the second        flex zone is greater than the bending stiffness of the third        flex zone, for providing distal pushability of portions of the        core member distal to the first flex zone,    -   the spiral cut of the tube has (i) a first pitch in the first        flex zone, (ii) a second pitch in the second flex zone, (iii) a        third pitch in the third flex zone, and (iv) changing in the        first transition zone from the first pitch to the second pitch        in a series of pitch transitions and (v) in the second        transition zone from the second pitch to the third pitch in a        series of pitch transitions for preventing buckling of the tube        in the first and second transition zones when the tube is        pushed; and    -   a stent carried by the intermediate portion.

Embodiment 57. The system of Embodiment 56, wherein the spiral cut ofthe tube prevails along a cut length of the tube, the cut length beinggreater than 50 cm.

Embodiment 58. The system of Embodiment 57, wherein the spiral cut iscontiguous along the cut length.

Embodiment 59. The system of Embodiment 58, further comprising apolymeric outer layer disposed over the outer surface of the tube alongat least a portion of the cut length, wherein the spiral cut is not cutinto the polymeric outer layer.

Embodiment 60. The system of Embodiment 59, wherein the polymeric outerlayer covers the entire cut length of the tube.

Embodiment 61. The system of Embodiment 56, wherein the tube comprisesan uncut segment at a distal portion of the tube.

Embodiment 62. A method of operating a stent delivery system, the methodcomprising:

-   -   inserting a core member comprising a varying-stiffness elongate        tube into a tortuous catheter,    -   advancing the tube through the tortuous catheter by bending the        tube in a transition zone of the tube, thereby forming a        curving, non-kinking bend in the transition zone.

Embodiment 63. The method of Embodiment 62, wherein the transition zoneis located between two flex zones of the tube.

Embodiment 64. The method of Embodiment 63, wherein one or both flexzones has a substantially constant bending stiffness.

Embodiment 65. The method of Embodiment 62, wherein the tube isspiral-cut along a cut length of the tube, and the cut length is greaterthan 50 cm.

Embodiment 66. The method of Embodiment 65, wherein the spiral cut ofthe tube is contiguous along the cut length.

Embodiment 67. The method of Embodiment 62, wherein advancing the tubecomprises navigating the tube through the aortic arch.

Embodiment 68. The method of Embodiment 62, wherein advancing the tubecomprises navigating the tube through the carotid siphon.

Embodiment 69. The method of Embodiment 62, performed with the coremember of any of s 1-Embodiment 61.

Embodiment 70. The method of Embodiment 62, wherein the catheter extendsinto the internal carotid artery, and advancing the tube comprisesnavigating a portion of the core member through the internal carotidartery without buckling the tube.

Embodiment 71. A stent delivery system, comprising:

-   -   an elongate core member sized for insertion into a blood vessel,        the core member configured for advancing a stent toward a        treatment location in the blood vessel, the core member        comprising a longitudinally extending tube having a helical cut        extending along the tube, the helical cut having an axial length        of at least 50 cm and being continuous along the axial length.

Embodiment 72. The system of Embodiment 71, wherein the helical cutcomprises a void in the shape of a helix that extends along the axiallength of the tube, wherein the void is continuous along the axiallength.

Embodiment 73. The system of Embodiment 72, wherein the void comprisesmultiple helical slots.

Embodiment 74. The system of Embodiment 73, wherein the helical slotsare arranged in a contiguous, end-to-end manner.

Embodiment 75. The system of Embodiment 74, wherein the void furthercomprises at least one connection aperture that joins adjacent helicalslots.

Embodiment 76. The system of Embodiment 75, wherein the helical slotsand the at least one connection aperture together form the continuousvoid.

Embodiment 77. The system of Embodiment 74, wherein the at least oneconnection aperture is a circle.

Embodiment 78. The system of Embodiment 77, wherein the at least oneconnection aperture has a diameter of about 100 microns.

Embodiment 79. The system of Embodiment 77, wherein the at least oneconnection aperture has a diameter of greater than 50 microns.

Embodiment 80. The system of Embodiment 77, wherein the at least oneconnection aperture has a diameter at least twice a width of a helicalslot.

Embodiment 81. The system of Embodiment 73, wherein each of the helicalslots has a slot width of about 25 microns.

Embodiment 82. The system of Embodiment 73, wherein at least one of thehelical slots has a slot width of about 70 microns or less.

Embodiment 83. The system of Embodiment 71, wherein the helical cutforms a cut pattern.

Embodiment 84. The system of Embodiment 71, wherein the tube has adiameter of 2.3 mm or less.

Embodiment 85. The system of Embodiment 71, wherein the tube has a wallthickness of 0.010″ or less.

Embodiment 86. A stent delivery system comprising a hypotube having anelongate tubular body having a first section and a continuous helicalcut extending about the first section, the cut having an axial length ofat least 50 cm.

Embodiment 87. The system of Embodiment 86, wherein the cut comprises aplurality of individual helical slots interconnected in an end-to-endmanner.

Embodiment 88. The system of Embodiment 87, wherein each individualhelical slot has an axial length of less than or equal to about 15 cm.

Embodiment 89. The system of Embodiment 87, wherein adjacent individualhelical slots interconnect via an aperture extending through thehypotube, the adjacent individual helical slots extending from theaperture.

Embodiment 90. The system of Embodiment 86, further comprising a secondsection, proximal to the first section, wherein a proximal end of thecut terminates proximal to the second section.

Embodiment 91. The system of Embodiment 86, wherein the tube furthercomprises an uncut region distal to the cut.

Embodiment 92. The system of Embodiment 86, wherein a pitch of thehelical cut varies over the length of the cut.

Embodiment 93. The system of Embodiment 92, the pitch of the helical cutchanges from a first pitch to a second pitch within a longitudinalsegment length of about 5 mm or less.

Embodiment 94. The system of Embodiment 92, the pitch of the helical cutchanges from a first pitch to a second pitch within a longitudinalsegment length of about 3 mm or less.

Embodiment 95. The system of Embodiment 92, the pitch of the helical cutchanges from a first pitch to a second pitch within a longitudinalsegment length of about 2 mm or less.

Embodiment 96. The system of Embodiment 92, the pitch of the helical cutchanges from a first pitch to a second pitch within a longitudinalsegment length of about 1.0 mm.

Embodiment 97. The system of Embodiment 92, wherein the pitch of thehelical cut changes within a longitudinal distance of about 10 cm ormore from an endpoint of the cut.

Embodiment 98. The system of Embodiment 92, wherein the pitch of thehelical cut changes within a longitudinal distance of about 20 cm ormore from an endpoint of the cut.

Embodiment 99. The system of Embodiment 92, wherein the pitch of thehelical cut changes within a longitudinal distance of about 30 cm ormore from an endpoint of the cut.

Embodiment 100. The system of Embodiment 92, wherein the pitch of thehelical cut changes in magnitude from a first segment to a secondsegment by 0.2 mm/rotation or less.

Embodiment 101. The system of Embodiment 92, wherein the pitch of thehelical cut changes in magnitude from a first segment to a secondsegment by 0.1 mm/rotation or less.

Embodiment 102. The system of Embodiment 92, wherein the pitch of thehelical cut changes in magnitude from a first segment to a secondsegment by 0.01 mm/rotation or less.

Embodiment 103. The system of Embodiment 92, wherein the pitch of thehelical cut changes in magnitude from a first segment to a secondsegment by 0.005 mm/rotation or less.

Embodiment 104. A method of manufacturing a stent delivery system, themethod comprising:

-   -   mounting a hypotube in a cutting device having a cutting head;    -   aligning the hypotube with the cutting head; and    -   while rotating and axially moving the hypotube relative to the        cutting head, cutting the hypotube to form a helically extending        cut having an axial length of at least 50 cm.

Embodiment 105. The method of Embodiment 104, wherein the cuttingcomprises cutting multiple helical slots to form the helically extendingcut.

Embodiment 106. The method of Embodiment 105, wherein the cuttingcomprises cutting the helical slots in a contiguous, end-to-end manner.

Embodiment 107. The method of Embodiment 106, wherein the cuttingcomprises cutting at least one connection aperture at an end of ahelical slot.

Embodiment 108. The method of Embodiment 107, wherein the aligning thecutting head with the at least one connection aperture to begin cuttinga subsequent helical slot from the at least one connection aperture.

Embodiment 109. The method of Embodiment 107, wherein the cutting atleast one connection aperture comprises cutting a circle at an end of ahelical slot.

Embodiment 110. The method of Embodiment 104, further comprisingreleasing the hypotube and repositioning and remounting the hypotube inthe cutting device after completing a cut.

Embodiment 111. The method of Embodiment 110, wherein the repositioningand remounting comprises aligning the cutting head with an end of thecut.

Embodiment 112. The method of Embodiment 110, wherein the cutting thehypotube comprises making three or more contiguous, end-to-end cuts tocreate the helically extending cut.

Embodiment 113. A method of operating a stent delivery system, themethod comprising:

-   -   inserting a core member into a catheter in a tortuous        configuration, the core member comprising a longitudinally        extending tube having a helical cut extending along the tube,        the helical cut having an axial length of at least 50 cm and        being continuous along the axial length; and    -   pushing the core member through the tortuous catheter; and    -   by pushing the core member, causing the tube to flex along the        helical cut, thereby facilitating advancement of the core member        through the tortuous catheter.

Embodiment 114. The method of Embodiment 113, wherein the core membercomprises a plurality of flex zones, and the pushing comprises advancingat least one flex zone across a tortuosity of the catheter such that thetube forms a curving, non-kinking bend across the tortuosity.

Embodiment 115. The method of Embodiment 113, wherein a pitch of thehelical cut varies over the length of the cut to provide a variableflexibility to the tube during advancement through the tortuouscatheter.

Embodiment 116. The method of Embodiment 113, wherein inserting the coremember into the catheter comprises doing so without buckling the tube.

Embodiment 117. The method of Embodiment 113, wherein the tube has anoutside diameter of 2.3 mm or less.

Embodiment 118. The method of Embodiment 113, wherein the tube has awall thickness of 0.010″ or less.

Embodiment 119. The method of Embodiment 113, wherein pushing the coremember through the catheter comprises moving a stent through thecatheter with the core member.

Embodiment 120. The method of Embodiment 119, further comprisingreleasing the stent from the core member.

Embodiment 121. The method of Embodiment 113, wherein pushing the coremember through the tortuous catheter comprises pushing the tube throughthe tortuous catheter.

Embodiment 122. A method of operating a stent delivery system, themethod comprising:

-   -   inserting a core member into a blood vessel of a patient, the        core member comprising a longitudinally extending tube having a        helical cut extending along the tube and an axial length of at        least 50 cm, the helical cut being continuous along the axial        length;    -   advancing the core member to the internal carotid artery; and    -   by advancing the core member, causing the tube to flex along the        helical cut, thereby facilitating advancement of the core member        to the internal carotid artery.

Embodiment 123. The method of Embodiment 122, further comprisingdistally advancing the core member through the internal carotid arteryto the middle cerebral artery of the patient.

Embodiment 124. The method of Embodiment 122, wherein the core membercomprises a plurality of flex zones, and the method further comprisesadvancing at least one flex zone across the aortic arch such that thetube forms a curving, non-kinking bend across the aortic arch.

Embodiment 125. The method of Embodiment 122, further comprisingdistally advancing the core member through the carotid siphon.

Embodiment 126. The method of Embodiment 122, wherein the cut length isgreater than 60 cm.

Embodiment 127. The method of Embodiment 122, wherein a pitch of thehelical cut varies over the length of the cut to provide a variableflexibility to the tube during advancement through the blood vessel.

Embodiment 128. The method of Embodiment 122, wherein advancing the coremember to the internal carotid artery comprises doing so withoutbuckling the tube.

Embodiment 129. The method of Embodiment 122, wherein the tube has anoutside diameter of 2.3 mm or less.

Embodiment 130. The method of Embodiment 122, wherein the tube has awall thickness of 0.010″ or less.

Embodiment 131. The method of Embodiment 122, wherein advancing the coremember comprises moving a stent with the core member.

Embodiment 132. The method of Embodiment 131, further comprisingreleasing the stent from the core member.

Embodiment 133. The method of Embodiment 122, wherein advancing the coremember to the internal carotid artery comprises positioning the tube sothat it extends from the aortic arch to the internal carotid artery.

Embodiment 134. The method of Embodiment 122, wherein advancing the coremember to the internal carotid artery comprises advancing the tube tothe internal carotid artery.

Embodiment 135. A stent delivery system, comprising:

-   -   a core member having a distal segment;    -   a stent engagement member positioned along the core member        distal segment and coupled to the core member, the engagement        member comprising an outer surface; and    -   a stent extending along the core member distal segment such that        the outer surface of the engagement member engages an inner        surface of the stent along at least a portion of only a distal        half of the stent for transmitting an axial force from the core        member to only the stent distal half.

Embodiment 136. The system of Embodiment 135, wherein an axial force onthe core member is transmitted to the stent only through the engagementmember.

Embodiment 137. The system of Embodiment 135, wherein a proximal end ofthe engagement member is positioned distal to a midpoint of the stentsuch that transmission of a distal axial force allows the engagementmember to pull the stent.

Embodiment 138. The system of Embodiment 135, wherein the engagementmember is rotatably coupled to the core member.

Embodiment 139. The system of Embodiment 135, wherein the engagementmember is positioned in an axial gap between restraints, coupled to thecore member, for permitting rotational movement of the engagement memberrelative to the core member.

Embodiment 140. The system of Embodiment 139, wherein the positioning ofthe engagement member in the axial gap permits translation movement ofthe engagement member relative to the core member.

Embodiment 141. The system of Embodiment 135, wherein the engagementmember is a first engagement member, and the system further comprises asecond stent engagement member coupled to the core member and positionedproximal to the first stent engagement member.

Embodiment 142. The system of Embodiment 141, wherein a distal end ofthe second stent engagement member is positioned proximal to a midpointof the stent such that transmission of a distal axial force allows thesecond stent engagement member to push the stent.

Embodiment 143. The system of Embodiment 141, wherein the second stentengagement member is rotatably coupled to the core member.

Embodiment 144. The system of Embodiment 141, wherein the second stentengagement member is positioned in an axial gap between restraints,coupled to the core member, for permitting rotational movement of thesecond stent engagement member relative to the core member.

Embodiment 145. The system of Embodiment 144, wherein the positioning ofthe second stent engagement member in the axial gap permits translationmovement of the second stent engagement member relative to the coremember.

Embodiment 146. The system of Embodiment 135, wherein the engagementmember comprises a generally tubular body.

Embodiment 147. The system of Embodiment 135, further comprising aradially expandable member coupled to the core member proximal to theengagement member, the radially expandable member having a collapsedposition and an expanded position, wherein in the expanded position, theradially expandable member is configured to engage a proximal portion ofthe stent.

Embodiment 148. The system of Embodiment 147, wherein the radiallyexpandable member comprises a balloon coupled to the core memberproximal to the engagement member, the balloon being inflatable toengage a proximal portion of the stent.

Embodiment 149. The system of Embodiment 148, wherein the core membercomprises an inflation lumen extending axially to the balloon.

Embodiment 150. The system of Embodiment 147, wherein the radiallyexpandable member comprises a wedge component having an outer portionconfigured to expand radially when the core member is proximallyrefracted such that the wedge component engages with the stent totransmit a proximal force to the stent.

Embodiment 151. The system of Embodiment 135, further comprising a stentcover component having a first end coupled to the core member distalsegment and a second end extending from the first end, the second endconfigured to at least partially surround at least a distal portion of astent carried by the stent delivery system.

Embodiment 152. The system of Embodiment 151, wherein the covercomponent first end is positioned in an axial gap between first andsecond restraints such that the first end is rotatably coupled to thecore member distal segment.

Embodiment 153. The system of Embodiment 151, wherein a distal end ofthe engagement member is spaced less than 1 mm proximal to the secondend of the cover component.

Embodiment 154. The system of Embodiment 151, wherein a distal end ofthe engagement member is spaced distal to the second end of the covercomponent such that the second end is configured to at least partiallysurround a portion of the engagement member.

Embodiment 155. The system of Embodiment 151, wherein a proximal end ofthe engagement member is positioned adjacent to the second end of thecover component such that the cover component extends longitudinallyalong an entire length of the engagement member.

Embodiment 156. The system of Embodiment 135, further comprising acatheter having a lumen configured to receive the core member,engagement member, and stent, wherein the stent is radially compressedbetween an inner surface of the catheter and the outer surface.

Embodiment 157. The system of Embodiment 135, wherein the stent is aself-expanding stent.

Embodiment 158. The system of Embodiment 135, further comprising aretraction-only interface positioned along the core member distalsegment proximal of the stent engagement member.

Embodiment 159. The system of Embodiment 158, wherein theretraction-only interface comprises a balloon.

Embodiment 160. The system of Embodiment 158, wherein theretraction-only interface comprises an expandable pad.

Embodiment 161. A stent delivery system, comprising:

-   -   a catheter having a lumen and an inner surface extending along        the lumen; a core member, extending within the catheter lumen,        having a distal segment and a device interface; and    -   a stent extending along the core member distal segment, at least        a portion of only a distal half of the stent being radially        compressed between the interface and the catheter inner surface        such that a distal axial force exerted on the core member is        transmitted through the interface to pull the stent in a distal        direction.

Embodiment 162. The system of Embodiment 161, wherein a proximal end ofthe interface is positioned distal to a midpoint of the stent.

Embodiment 163. The system of Embodiment 161, wherein the interfacecomprises a stent engagement member coupled to the distal segment of thecore member, the engagement member comprising an outer surfaceconfigured to engage an inner surface of the stent.

Embodiment 164. The system of Embodiment 161, wherein the deviceinterface is a first device interface, and the system further comprisesa second device interface, proximal to the first device interface,configured to engage the stent along a proximal half thereof.

Embodiment 165. The system of Embodiment 164, wherein the second deviceinterface comprises a second stent engagement member coupled to thedistal segment of the core member, the second stent engagement membercomprising an outer surface configured to engage an inner surface of thestent.

Embodiment 166. The system of Embodiment 164, wherein the second deviceinterface comprises an expandable member coupled to the core memberproximal to the first stent engagement member, the radially expandablemember having a collapsed position and an expanded position, wherein inthe expanded position, the radially expandable member is configured toengage a proximal portion of the stent.

Embodiment 167. The system of Embodiment 166, wherein the radiallyexpandable member comprises a balloon coupled to the core memberproximal to the first stent engagement member, the balloon beinginflatable to engage a proximal portion of the stent.

Embodiment 168. The system of Embodiment 164, wherein the second deviceinterface comprises a retraction-only interface.

Embodiment 169. The system of Embodiment 168, wherein theretraction-only interface comprises a balloon.

Embodiment 170. The system of Embodiment 168, wherein theretraction-only interface comprises an expandable pad.

Embodiment 171. The system of Embodiment 161, further comprising a stentcover component having a first end coupled to the core member distalsegment and a second end extending from the first end, the second endconfigured to at least partially surround at least a distal portion of astent carried by the stent delivery system.

Embodiment 172. The system of Embodiment 171, wherein a distal end ofthe interface is spaced less than 1 mm proximal to the second end of thecover component.

Embodiment 173. The system of Embodiment 171, wherein a distal end ofthe interface is spaced distal to the second end of the cover componentsuch that the second end is configured to at least partially surround aportion of the interface.

Embodiment 174. The system of Embodiment 171, wherein a proximal end ofthe interface is positioned adjacent to the second end of the covercomponent such that the cover component extends longitudinally along anentire length of the interface.

Embodiment 175. A method of advancing a stent delivery assembly througha tortuous catheter, the method comprising:

-   -   moving a core assembly distally within a lumen of the catheter,        the core assembly comprising a stent engagement member that is        engaged with at least a portion of a stent along only a distal        half of the stent;    -   by moving the core assembly, pulling the stent distally within        the catheter lumen, the engagement member configured such that        friction between the engagement member and the core member is        less than friction between the engagement member and the stent.

Embodiment 176. The method of Embodiment 175, wherein the movingcomprises causing the stent to rotate with respect to a core member ofthe core assembly.

Embodiment 177. The method of Embodiment 176, further comprisingrotating the core member to steer the core assembly to avoid damagingvasculature adjacent to a treatment site within a blood vessel.

Embodiment 178. The method of Embodiment 175, further comprisingapplying a proximally oriented retracting force on the core assembly toretract the stent into the catheter after a distal portion of the stenthas been expanded outside of the catheter.

Embodiment 179. The method of Embodiment 178, wherein the applyingcomprises inflating a balloon, coupled to a core member of the coreassembly, to engage a proximal portion of the stent prior to applyingthe proximally oriented force.

Embodiment 180. The method of Embodiment 175, further comprisingadvancing the core assembly distally until at least a distal portion ofthe stent extends distally beyond the catheter such that the stentdistal portion expands from a collapsed configuration.

Embodiment 181. The method of Embodiment 180, wherein the advancingcomprises inflating a balloon, coupled to a core member of the coreassembly, to engage a proximal portion of the stent prior to advancingthe stent distal portion distally beyond the catheter.

Embodiment 182. The method of Embodiment 181, wherein the advancingcomprises, after the stent distal end extends distally beyond thecatheter, advancing the stent by transferring a distal pushing force tothe stent via the balloon until a proximal portion of the stent isdistally beyond the catheter.

Embodiment 183. The method of Embodiment 175, further comprisingpartially expanding the stent distally of the catheter, and retractingthe stent into the catheter with a retraction-only interface.

Embodiment 184. The method of Embodiment 183, wherein pulling the stentdistally comprises doing so without applying any substantial distalpulling force to the stent by the retraction-only interface.

Embodiment 185. A stent delivery system, comprising:

-   -   a core member having a first section and a second section distal        to the first section, the second section having a bending        stiffness per unit length that is less than a bending stiffness        per unit length of the first section;    -   an introducer sheath having a lumen configured to receive the        core member therethrough, the introducer sheath having a length        of at least about 80 cm; and    -   a microcatheter having a lumen and a proximal end configured to        interface with a distal end of the introducer sheath for        delivering the core member into the microcatheter lumen.

Embodiment 186. The system of Embodiment 185, wherein the sheath lengthis equal to or greater than a length of the core member second section.

Embodiment 187. The system of Embodiment 185, wherein the first sectionhas a substantially constant bending stiffness per unit length.

Embodiment 188. The system of Embodiment 185, wherein the sheath lengthis between about 80 cm and about 150 cm.

Embodiment 189. The system of Embodiment 188, wherein the sheath lengthis about 106 cm.

Embodiment 190. The system of Embodiment 185, wherein the core membercomprises a marker visible through the introducer sheath.

Embodiment 191. The system of Embodiment 190, wherein the marker isdisposed along the core member in the first section thereof.

Embodiment 192. The system of Embodiment 190, wherein the introducersheath comprises titanium dioxide.

Embodiment 193. The system of Embodiment 185, wherein the core membercomprises a solid wire in the first section.

Embodiment 194. The system of Embodiment 185, wherein the core membercomprises a hollow tubular member in the second section.

Embodiment 195. The system of Embodiment 194, wherein at least a portionof the hollow tubular member comprises a spiral cut.

Embodiment 196. The system of Embodiment 195, wherein the spiral cutextends along about 60 cm to about 100 cm of a length of the secondsection.

Embodiment 197. The system of Embodiment 196, wherein the spiral cutextends along about 86 cm of the length of the second section.

Embodiment 198. A stent delivery system, comprising:

-   -   a core member having (i) a stiff section having a first bending        stiffness and (ii) a soft section having a second bending        stiffness that is less than the first bending stiffness, the        second bending stiffness varying spatially along the soft        section;    -   an introducer sheath covering any portion of the core member        having a bending stiffness that is less than the first bending        stiffness, the introducer sheath having a length of at least        about 80 cm; and    -   a microcatheter having a lumen and a proximal end configured to        interface with a distal end of the introducer sheath for        delivering the core member into the microcatheter lumen.

Embodiment 199. The system of Embodiment 198, wherein the bendingstiffness of the stiff section is substantially constant.

Embodiment 200. The system of Embodiment 198, wherein the stiff sectionis proximal to the soft section.

Embodiment 201. The system of Embodiment 198, wherein the sheath lengthis between about 80 cm and about 150 cm.

Embodiment 202. The system of Embodiment 201, wherein the sheath lengthis about 106 cm.

Embodiment 203. A method of manufacturing a stent delivery system, themethod comprising:

-   -   providing a core member and an introducer sheath configured to        extend over the core member, the core member comprising a stiff        proximal section configured to allow a clinician to grasp the        core member for advancing the core member relative to the        sheath; and    -   inserting the core member into the sheath such that the sheath        covers any portion of the core member having a bending stiffness        less than a bending stiffness of the proximal section and such        that only the proximal section is exposed for gripping.

Embodiment 204. The method of Embodiment 203, wherein the insertingcomprises advancing the core member into the sheath until a proximal endof the sheath is positioned axially over a distal end of the stiffproximal section.

Embodiment 205. The method of Embodiment 203, wherein the insertingcomprises aligning a marker on the core member with a proximal end ofthe sheath.

Embodiment 206. A method of advancing a stent delivery system, themethod comprising:

-   -   positioning a distal end of the stent delivery assembly adjacent        to a proximal end of a guide catheter for moving the core member        into a lumen of the catheter, the core member comprising a        proximal first section and a distal second section that is more        flexible than the first section, the stent delivery assembly        comprising an introducer sheath extending over the entire distal        second section; and    -   while grasping a proximal end of the introducer sheath, grasping        only the core member first section to apply a distal axial force        to advance the core member into the catheter lumen.

Embodiment 207. The method of Embodiment 206, wherein the core membercomprises a marker visible through the introducer sheath, the methodfurther comprising advancing the core member into the catheter lumenuntil the marker reaches a first position visible within the introducersheath, the first position of the marker corresponding to a position ofa stent carried on the core member within the catheter.

Embodiment 208. The method of Embodiment 206, further comprisingproximally withdrawing the introducer sheath from over the core memberwhen the marker reaches the first position.

Embodiment 209. A stent delivery system, comprising:

-   -   a core member having a distal segment;    -   a stent engagement member having a generally tubular body        positioned about the core member distal segment and rotatably        coupled to the core member, the engagement member comprising an        inner layer having a first durometer and an outer layer having a        second durometer less than the first durometer; and    -   a stent extending along the core member distal segment such that        an inner surface of the stent is engaged by the engagement        member outer layer for facilitating rotation of the stent        relative to the core member.

Embodiment 210. The system of Embodiment 209, wherein the inner layercomprises a substantially cylindrical inner surface surrounding the coremember.

Embodiment 211. The system of Embodiment 209, wherein the inner layercomprises a coil.

Embodiment 212. The system of Embodiment 209, wherein the outer layercomprises a durometer of between about 10 A to about 50 A.

Embodiment 213. The system of Embodiment 212, wherein the outer layercomprises a durometer of between about 15 A to about 40 A.

Embodiment 214. The system of Embodiment 213, wherein the outer layercomprises a durometer of about 20 A.

Embodiment 215. The system of Embodiment 209, wherein the inner layercomprises polyimide and the outer layer comprises silicone.

Embodiment 216. The system of Embodiment 209, wherein the outer layercomprises a substantially cylindrical outer surface for contacting thestent.

Embodiment 217. The system of Embodiment 209, wherein the outer layercomprises a plurality of protrusions for contacting the stent.

Embodiment 218. The system of Embodiment 209, wherein the outer layer isadhered to the inner layer.

Embodiment 219. The system of Embodiment 209, wherein the stent ismoveable within a tubular component by virtue of engagement with theengagement member.

Embodiment 220. The system of Embodiment 209, further comprising asheath having a lumen configured to receive the core member, engagementmember, and stent, wherein the stent is radially compressed between aninner surface of the sheath and the engagement member outer layer.

Embodiment 221. The system of Embodiment 220, wherein friction betweenthe engagement member and the stent is greater than friction between thesheath inner surface and the stent.

Embodiment 222. The system of Embodiment 209, wherein the engagementmember comprises a pad.

Embodiment 223. The system of Embodiment 209, wherein the stent is aself-expanding stent.

Embodiment 224. A stent delivery system, comprising:

-   -   a core member having a distal segment;    -   a stent engagement member positioned about the core member        distal segment and rotatably coupled to the core member, the        engagement member comprising an inner layer and an outer layer        having a durometer of less than 50 A; and    -   a stent extending along the core member distal segment such that        an inner surface of the stent is engaged by the engagement        member outer layer for facilitating rotation of the stent        relative to the core member.

Embodiment 225. The system of Embodiment 224, wherein the inner layercomprises a substantially cylindrical inner surface surrounding the coremember.

Embodiment 226. The system of Embodiment 224, wherein the inner layercomprises a coil.

Embodiment 227. The system of Embodiment 224, wherein the outer layercomprises a durometer of between about 10 A to about 50 A.

Embodiment 228. The system of Embodiment 227, wherein the outer layercomprises a durometer of between about 15 A to about 40 A.

Embodiment 229. The system of Embodiment 228, wherein the outer layercomprises a durometer of about 20 A.

Embodiment 230. The system of Embodiment 224, wherein the inner layercomprises a durometer of between about 70 A to about 100 A.

Embodiment 231. The system of Embodiment 224, wherein the inner layercomprises polyimide and the outer layer comprises silicone.

Embodiment 232. A method of manufacturing a stent delivery system, themethod comprising:

-   -   forming a tubular body of a first material having a first        durometer; and    -   dipping the tubular body in a second material to form an outer        layer of the second material on the body, wherein the second        material, when in solid form, has a second durometer less than        the first durometer.

Embodiment 233. The method of Embodiment 232, wherein the formingcomprises dipping a wire in the first material to form the tubular body.

Embodiment 234. The method of Embodiment 233, wherein the dipping thewire comprises dipping the wire in polyimide to form the tubular body.

Embodiment 235. The method of Embodiment 233, wherein the dipping thewire comprises repeatedly dipping the wire such that the tubular bodyhas an outer diameter of from about 0.343 mm to about 0.380 mm.

Embodiment 236. The method of Embodiment 233, wherein the formingcomprises selecting a wire having an outer diameter of less than orequal to 0.25 mm.

Embodiment 237. The method of Embodiment 232, wherein the dippingcomprises repeatedly dipping the tubular body in the second materialsuch that the outer layer has an outer diameter of about 0.579 mm toabout 0.635 mm.

Embodiment 238. The method of Embodiment 232, wherein the dippingcomprises dipping the tubular body in silicone, ChronoPrene, Pebax®, orpolyurethane.

Embodiment 239. The method of Embodiment 232, further comprising cuttingthe tubular body to form an engagement member.

Embodiment 240. The method of Embodiment 239, wherein the cuttingcomprises cutting the tubular body to a length of from about 2.1 mm toabout 2.5 mm.

Embodiment 241. The method of Embodiment 239, further comprisingpositioning the engagement member over a core member of the stentdelivery system.

Embodiment 242. A method of advancing a stent delivery assembly througha tortuous catheter, the method comprising:

-   -   moving a core assembly distally within a lumen of the catheter;    -   by moving the core assembly, moving a stent distally within the        catheter lumen;    -   by moving the core assembly, causing the stent, together with        and supported on a stent engagement member of the core assembly,        to rotate with respect to a core member of the core assembly,        the engagement member being configured such that friction        between the engagement member and the core member is less than        friction between the engagement member and the stent.

Embodiment 243. The method of Embodiment 242, wherein the movingcomprises contacting an inner layer of the engagement member with thecore member and an outer layer of the engagement member with the stent,wherein the causing the stent to rotate about the core member comprisescausing the inner layer to rotate or slide with respect to the coremember while the outer layer is substantially stationary with respect tothe stent.

Embodiment 244. The method of Embodiment 242, further comprisingrotating the core member to steer the core assembly to avoid damagingvasculature adjacent to a treatment site within a blood vessel.

Embodiment 245. The method of Embodiment 242, wherein the movingcomprises distally advancing the core assembly through the aortic archof a patient.

Embodiment 246. A stent delivery system, comprising:

-   -   a microcatheter having a lumen with an internal diameter;    -   a core member having a proximal segment and a distal segment,        the proximal segment comprising a hollow, tubular portion having        an external diameter such that the tubular portion fills a        majority of space in the microcatheter lumen; and    -   a stent carried on the core member distal segment such that        distal advancement or proximal withdrawal of the core member        results in distal advancement or proximal withdrawal,        respectively, of the stent within the microcatheter;    -   wherein the core member tubular portion provides core member        pushability by providing (i) column strength to the core member        during distal advancement within the microcatheter and (ii)        radial support of the tubular portion against a wall of the        microcatheter lumen to reduce buckling tendency of the core        member.

Embodiment 247. The system of Embodiment 246, wherein the tubularportion external diameter is between about 60% and about 98% of themicrocatheter internal diameter.

Embodiment 248. The system of Embodiment 246, wherein the tubularportion external diameter is between about 75% and about 95% of themicrocatheter internal diameter.

Embodiment 249. The system of Embodiment 248, wherein the tubularportion external diameter is between about 90% and about 93% of themicrocatheter internal diameter.

Embodiment 250. The system of Embodiment 246, wherein the tubularportion external diameter is between about 0.35 mm to about 0.70 mm.

Embodiment 251. The system of Embodiment 250, wherein the tubularportion external diameter is between about 0.45 mm to about 0.65 mm.

Embodiment 252. The system of Embodiment 251, wherein the tubularportion external diameter is about 0.51 mm.

Embodiment 253. The system of Embodiment 246, wherein the proximalsegment comprises a solid core wire coupled to a proximal end of thetubular portion.

Embodiment 254. The system of Embodiment 253, wherein the proximalsegment comprises a sheath extending from a proximal end of the distalsegment to the proximal end of the tubular portion.

Embodiment 255. The system of Embodiment 254, wherein the proximalsegment comprises a solid core wire coupled to a proximal end of thetubular portion and the sheath is bonded to the solid core wire and to adistal end of the tubular portion.

Embodiment 256. The system of Embodiment 254, wherein an assembly of thesheath and the proximal segment has an outer diameter of about 0.61 mm.

Embodiment 257. The system of Embodiment 246, wherein the distal segmentcomprises a core wire and the proximal segment comprises a tubularmember coupled to the core wire.

Embodiment 258. The system of Embodiment 246, wherein the tubularportion comprises a helical cut extending along an axial length of atleast 50 cm.

Embodiment 259. A method of advancing a stent delivery system through atorturous microcatheter, the method comprising:

-   -   moving a core assembly distally within a lumen of the        microcatheter, the lumen having an internal diameter;    -   by moving the core assembly, moving a core member distally        within the microcatheter lumen, the core member having a        proximal segment and a distal segment, the proximal segment        comprising a hollow, tubular portion having an external diameter        such that the tubular portion fills a majority of space in the        microcatheter lumen;    -   by moving the core assembly, forcing the tubular portion into        radial contact with a wall of the microcatheter lumen such that        the tubular portion is operative to (i) provide column strength        to the core member during distal advancement within the        microcatheter and (ii) reduce buckling tendency of the core        member.

Embodiment 260. The method of Embodiment 259, further comprisingdistally advancing the core assembly such that a stent carried by thecore assembly is permitted to extend out of the microcatheter andexpand.

Embodiment 261. The method of Embodiment 260, further comprisingproximally retracting the core member prior to releasing the stent suchthat the stent is recaptured to within the microcatheter.

Embodiment 262. A stent delivery system, comprising:

-   -   a core member having a distal segment;    -   first and second restraints coupled to the core member distal        segment and axially spaced apart from each other to provide an        axial gap, the first and second restraints each having an outer        profile that tapers radially inwardly, in a direction away from        the gap such that the first restraint tapers in a distal        direction and the second restraint tapers in a proximal        direction; and    -   a stent cover component having a first end positioned in the        axial gap between the first and second restraints such that the        first end is rotatably coupled to the core member distal        segment.

Embodiment 263. The system of Embodiment 262, wherein the stent covercomponent has at least one second end extending from the first end, theat least one second end being configured to at least partially surroundat least a distal portion of a stent carried by the stent deliverysystem.

Embodiment 264. The system of Embodiment 262, wherein the first end ofthe stent cover component is formed separately from the core member suchthat the first end is rotatable about and slidable along the core memberbetween the first and second restraints.

Embodiment 265. The system of Embodiment 262, wherein the firstrestraint is positioned distally of the second restraint, the firstrestraint having an outer profile that is less than an outer profile ofthe second restraint.

Embodiment 266. The system of Embodiment 265, wherein the firstrestraint has a maximum outer diameter less than a maximum outerdiameter of the second restraint.

Embodiment 267. The system of Embodiment 262, wherein the firstrestraint has a maximum outer diameter less than a maximumcross-sectional profile of the stent cover component.

Embodiment 268. The system of Embodiment 262, further comprising (i)third and fourth restraints rotatably coupled to the core member distalsegment and axially spaced apart from each other to provide a secondaxial gap and (ii) a stent engagement member rotatably coupled to thecore member distal segment in the second axial gap between the first andsecond restraints.

Embodiment 269. The system of Embodiment 268, wherein the stentengagement member is formed separately from the core member such that itcan rotate about and slide along the core member between the third andfourth restraints.

Embodiment 270. The system of Embodiment 269, further comprising a stentpositioned over and engaged by the stent engagement member such that thestent is freely rotatable about the core member.

Embodiment 271. The system of Embodiment 270, wherein the stent has aninner diameter, the inner diameter of the stent being greater thanmaximum cross-sectional profiles of the third and fourth restraints.

Embodiment 272. The system of Embodiment 269, further comprising a stentpositioned over and engaged by the stent engagement member, the stenthaving an inner diameter that is greater than maximum cross-sectionalprofiles of the third and fourth restraints.

Embodiment 273. The system of Embodiment 268, wherein the engagementmember has a maximum outer diameter, the maximum outer diameter of theengagement member being greater than maximum cross-sectional profiles ofthe third and fourth restraints.

Embodiment 274. The system of Embodiment 268, wherein the second axialgap has an axial length that is between about 0.30 mm and about 0.50 mmgreater than an axial length of the stent engagement member.

Embodiment 275. The system of Embodiment 274, wherein the axial lengthof the second axial gap is about 0.40 mm greater than the axial lengthof the stent engagement member.

Embodiment 276. The system of Embodiment 262, wherein the axial gap hasan axial length of between about 0.50 mm and about 0.70 mm.

Embodiment 277. The system of Embodiment 276, wherein the axial lengthof the axial gap is about 0.60 mm.

Embodiment 278. The system of Embodiment 262, further comprising anintroducer sheath having a lumen configured to receive the core member,the first and second restraints, and the stent cover component.

Embodiment 279. A stent delivery system, comprising:

-   -   a core member having a distal segment;    -   first and second restraints coupled to the core member distal        segment and axially spaced apart from each other to provide an        axial gap, the first and second restraints each having an outer        profile that tapers radially inwardly in directions away from        the gap; and    -   a stent engagement component at least partially disposed in the        axial gap between the first and second restraints such that the        component is slidably and rotatably coupled to the core member        distal segment.

Embodiment 280. The system of Embodiment 279, wherein the stentengagement component comprises a stent cover component having (i) afirst end positioned in the axial gap between the first and secondrestraints such that the first end is rotatably coupled to the coremember distal segment and (ii) at least one second end extending fromthe first end, the at least one second end being configured to at leastpartially surround at least a distal portion of a stent carried by thestent delivery system.

Embodiment 281. The system of Embodiment 279, wherein the stentengagement component comprises a stent engagement member rotatablycoupled to the core member distal segment in the gap between the firstand second restraints.

Embodiment 282. The system of Embodiment 281, wherein the first andsecond restraints have maximum outer cross-sectional profiles that areless than a maximum diameter of the stent engagement member.

Embodiment 283. The system of Embodiment 282, wherein the first andsecond restraints have different maximum outer cross-sectional profiles.

Embodiment 284. The system of Embodiment 279, further comprising (i) athird restraint spaced apart from the first and second restraints andproviding a second axial gap and (ii) a second stent engagementcomponent rotatably coupled to the core member distal segment in thesecond axial gap.

Embodiment 285. The system of Embodiment 279, further comprising a stentcarried by the core member, the stent having an inner diameter that isgreater than maximum cross-sectional profiles of the first and secondrestraints.

Embodiment 286. The system of Embodiment 279, wherein the deliverysystem comprises a first radiopaque marker, the catheter comprises asecond radiopaque marker, the first and second radiopaque markers beinglongitudinally movable relative to each other and longitudinallyalignable with each other such that the system achieves a pre-releaseposition beyond which additional distal advancement of the core memberpermits release of a stent from the delivery system.

Embodiment 287. The system of Embodiment 286, wherein the firstrestraint comprises the first radiopaque marker, and a distal portion ofthe catheter comprises the second radiopaque marker.

Embodiment 288. The system of Embodiment 287, wherein the secondradiopaque marker is positioned at the catheter distal end.

Embodiment 289. The system of Embodiment 287, wherein the firstrestraint is positioned distally of the second restraint.

Embodiment 290. A method of delivering a stent delivery system, themethod comprising:

-   -   inserting the delivery system into a curved path, the delivery        system comprising a catheter, a core member disposed within the        catheter, first and second restraints coupled to the core        member, a stent engagement component coupled to the core member        between the first and second restraints, and a stent having a        first portion (i) supported on the stent engagement component        and (ii) extending over at least one of the first and second        restraints, the first and second restraints each having a        longitudinally tapered end;    -   causing the core member to bend in the curved path, more than        the core member could if the first and second restraints were        not tapered, without causing the first and second restraints to        compress the stent against an inner wall of the catheter.

Embodiment 291. The method of Embodiment 290, wherein the firstrestraint is positioned distally of the second restraint, the methodfurther comprising advancing the core member until the first restraintis determined to be positioned adjacent to the distal end of thecatheter.

Embodiment 292. The method of Embodiment 291, further comprising holdingthe axial position of the core member relative to the catheter, when thefirst restraint is determined to be positioned adjacent to the distalend of the catheter, until initial placement of the stent is determinedto be correct.

Embodiment 293. The method of Embodiment 291, wherein the deliverysystem comprises a first radiopaque marker, the catheter comprises asecond radiopaque marker longitudinally movable relative to the firstradiopaque marker, and the advancing comprises longitudinally aligningthe first and second radiopaque markers such that the system achieves apre-release position beyond which additional distal advancement of thecore member permits release of the stent from the delivery system.

Embodiment 294. The method of Embodiment 293, wherein the firstrestraint comprises the first radiopaque marker, a distal portion of thecatheter comprises the second radiopaque marker, and the advancingcomprises observing an image of the first radiopaque marker and thesecond radiopaque marker as the core member is advanced relative to thecatheter.

Embodiment 295. The method of Embodiment 294, wherein the secondradiopaque marker is positioned at the catheter distal end, and theadvancing comprises longitudinally aligning the first restraint with thecatheter distal end.

Embodiment 296. The method of Embodiment 291, further comprisingadvancing the first and second restraints distally of the catheterdistal end such that the stent first portion is released and the stentis disengaged from the delivery system.

Embodiment 297. The method of Embodiment 290, wherein the stent firstportion undergoes a bend of at least about 30°.

Embodiment 298. The method of Embodiment 290, wherein the causingcomprises causing the stent first portion to undergo the bend withoutcausing the first and second restraints to contact an inner surface ofthe stent.

Embodiment 299. The method of Embodiment 290, wherein the causingcomprises causing the stent first portion to undergo a bend of at leastabout 45° without causing the first and second restraints to compressthe stent against the inner wall of the catheter.

Embodiment 300. The method of Embodiment 299, wherein the causingcomprises causing the stent first portion to undergo the bend withoutcausing the first and second restraints to contact an inner surface ofthe stent.

Embodiment 301. The method of Embodiment 290, wherein the causingcomprises causing the stent first portion to undergo a bend of at leastabout 60° without causing the first and second restraints to compressthe stent against the inner wall of the catheter.

Embodiment 302. The method of Embodiment 290, wherein the causingcomprises causing the stent first portion to undergo a bend of at leastabout 90° without causing the first and second restraints to compressthe stent against the inner wall of the catheter.

Embodiment 303. The method of Embodiment 290, wherein the causingcomprises causing the stent first portion to undergo a bend of at leastabout 110° without causing the first and second restraints to compressthe stent against the inner wall of the catheter.

Embodiment 304. The method of Embodiment 290, wherein the deliverysystem further comprises third and fourth restraints coupled to the coremember distally of the first and second restraints, the third and fourthrestraints being spaced apart to provide a gap wherein a first end of astent cover component is coupled to the core member, the stent firstportion extending over the first, second, and third restraints, whereinthe causing comprises causing the stent first portion to undergo thebend without causing the first, second, and third restraints to compressthe stent against the inner wall of the catheter.

Embodiment 305. The method of Embodiment 304, wherein the causingcomprises causing the stent first portion to undergo the bend withoutcausing the first, second, and third restraints to contact an innersurface of the stent.

Embodiment 306. The method of Embodiment 290, wherein the causingcomprises advancing the core member and the stent through the aorticarch.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andembodiments hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this specification, illustrate aspects of thedisclosure and together with the description serve to explain theprinciples of the subject technology.

FIG. 1 is a side, cross-sectional view of a medical device deliverysystem disposed within a body lumen, according to some embodiments.

FIG. 2 is a side, cross-sectional view of a core assembly of the medicaldevice delivery system shown in FIG. 1, according to some embodiments.

FIG. 3 is an enlarged side, cross-sectional view of the delivery systemshown in FIG. 1.

FIG. 4 is another enlarged side, cross-sectional view of the deliverysystem shown in FIG. 1.

FIG. 5 is a side, cross-sectional view of a medical device deliverysystem in a first position, adjacent to a target location, according tosome embodiments.

FIG. 6 is a side, cross-sectional view of the delivery system shown inFIG. 5, wherein the system is in a second position in which a stentthereof is partially expanded and a distal cover is disengaged from thestent, according to some embodiments.

FIG. 7 is a side, cross-sectional view of the delivery system shown inFIG. 5, wherein the distal cover is moved to an everted position,according to some embodiments.

FIG. 8 is a side, cross-sectional view of the delivery system shown inFIG. 5, wherein the stent has been retracted into a catheter of thesystem, according to some embodiments.

FIG. 9 is a side, cross-sectional view of the stent expanded at thetarget location, according to some embodiments.

FIGS. 10 and 11 are partial perspective views of an engagement member,according to some embodiments.

FIG. 12 is a side, cross-sectional view of a medical device deliverysystem being advanced through a torturous pathway, according to someembodiments.

FIG. 13 is another side, cross-sectional view of a core assembly,according to some embodiments.

FIG. 14 is a schematic view of a laser cutting machine performing alaser cut in a catheter.

FIG. 15 is a schematic view of a laser cutting machine performing alaser cut and a catheter, according to some embodiments.

FIG. 16 is an enlarged side view illustrating drawbacks of prior artmethods for creating a spiral cut in a tubular member.

FIG. 17 is an enlarged side view of contiguous or continuous spiral cutin a tubular member, according to some embodiments.

FIG. 18 is a flowchart illustrating representative steps of a method ofperforming a helical cut in a tubular member, according to someembodiments.

FIG. 19 is a schematic view of human vasculature, separated intorepresentative zones, according to some embodiments.

FIG. 20 is a schematic side view of human neurovasculaturerepresentative of some of the neurovasculature accessible withembodiments of the delivery systems disclosed herein.

FIG. 21 is a graph illustrating the relationship between cut pitch anddistance from a cut distal end of a helical cut in a tubular member,according to some embodiments.

FIG. 22 is a perspective view of a medical device delivery system,according to some embodiments.

FIGS. 23-25 are side views of a medical device delivery system,illustrating relative positions of a catheter, a sheath, and a coremember and a visible guide system, according to some embodiments.

FIG. 26 is a side, cross-sectional view of another core assembly,according to some embodiments.

FIG. 27 is a side, cross-sectional view of another core assembly,according to some embodiments.

FIGS. 28 and 29 are side, cross-sectional views of device interfaces forproviding enhanced proximal re-sheathing capability, according to someembodiments.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth to provide a full understanding of the subject technology. Itshould be understood that the subject technology may be practicedwithout some of these specific details. In other instances, well-knownstructures and techniques have not been shown in detail so as not toobscure the subject technology.

FIGS. 1-8 depict embodiments of a medical device delivery system 100which may be used to deliver and/or deploy a medical device, such as butnot limited to a stent 200, into a hollow anatomical structure such as ablood vessel 102. The stent 200 can comprise a proximal end 202 and adistal end 204. The stent 200 can comprise a braided stent or other formof stent such as a laser-cut stent, roll-up stent, etc. The stent 200can optionally be configured to act as a “flow diverter” device fortreatment of aneurysms, such as those found in blood vessels includingarteries in the brain or within the cranium, or in other locations inthe body such as peripheral arteries. The stent 200 can optionally besimilar to any of the versions or sizes of the PIPELINE™ EmbolizationDevice marketed by Covidien of Mansfield, Mass. USA. The stent 200 canfurther alternatively comprise any suitable tubular medical deviceand/or other features, as described herein.

As shown in FIG. 1, the depicted medical device delivery system 100 cancomprise an elongate tube or catheter 110 which slidably receives a coreassembly 140 configured to carry the stent 200 through the catheter 110.FIG. 2 illustrates the core assembly 140 without depicting the catheter110 for clarity. The depicted catheter 110 (see FIGS. 1, 3-8) has aproximal end 112 and an opposing distal end 114 which can be positionedat a treatment site within a patient, an internal lumen 116 extendingfrom the proximal end 112 to the distal end 114, and an inner surface118 facing the lumen 116. At the distal end 114, the catheter 110 has adistal opening 120 through which the core assembly 140 may be advancedbeyond the distal end 114 in order to expand or deploy the stent 200within the blood vessel 102. The proximal end 112 may include a catheterhub 122. The catheter 110 can define a generally longitudinal axis A-Aextending between the proximal end 112 and the distal end 114. When thedelivery system 100 is in use, the longitudinal axis need not bestraight along some or any of its length.

The catheter 110 can optionally comprise a microcatheter. For example,the catheter 110 can optionally comprise any of the various lengths ofthe MARKSMAN™ catheter available from Covidien of Mansfield, Mass. USA.The catheter 110 can optionally comprise a microcatheter having an innerdiameter of about 0.030 inches or less, and/or an outer diameter of 3French or less near the distal end 114. Instead of or in addition tothese specifications, the catheter 110 can comprise a microcatheterwhich is configured to percutaneously access the internal carotidartery, or a location within the neurovasculature distal of the internalcarotid artery, with its distal opening 120.

Information regarding additional embodiments of the catheter 110, andadditional details and components that can optionally be used orimplemented in the embodiments of the catheter described herein, can befound in U.S. Patent Application Publication No. US 2011/0238041 A1,published on Sep. 29, 2011, titled Variable Flexibility Catheter. Theentirety of the aforementioned publication is hereby incorporated byreference herein and made a part of this specification.

The core assembly 140 can comprise a core member 160 configured toextend generally longitudinally through the lumen 116 of the catheter110. The core member 160 can have a proximal end or section 162 and aterminal or distal end 164, which can include a tip coil 165. The coremember 160 can also comprise an intermediate portion 166 located betweenthe proximal end 162 and the distal end 164, which intermediate portionis the portion of the core member 160 onto or over which the stent 200is positioned or fitted or extends when the core assembly 140 is in thepre-deployment configuration as shown in FIGS. 1-5.

The core member 160 can generally comprise any member(s) with sufficientflexibility, column strength and thin-ness to move the stent 200 orother medical device through the catheter 110. The core member 160 cantherefore comprise a wire, or a tube such as a hypotube, or a braid,coil, or other suitable member(s), or a combination of wire(s), tube(s),braid(s), coil(s), etc. The embodiment of the core member 160 depictedin FIGS. 1-8 is of multi-member construction, comprising a proximal wire168, a tube 170 (e.g., a hypotube) connected at its proximal end to adistal end of the proximal wire 168, and a distal wire 172 connected atits proximal end to a distal end of the tube 170. An outer layer 174,which can comprise a layer of lubricious material such as PTFE(polytetrafluoroethylene or TEFLON™) or other lubricious polymers, cancover some or all of the tube 170 and/or proximal wire 168. The proximaland/or distal wires 168, 172 may taper or vary in diameter along some orall of their lengths. The proximal wire 168 may include one or morefluorosafe markers 176, and such marker(s) can be located on a portionof the wire 168 that is not covered by the outer layer 174, e.g.,proximal of the outer layer 174. This portion of the wire 168 marked bythe marker(s) 176, and/or proximal of any outer layer 174, can comprisea bare metal outer surface.

The core assembly 140 can further comprise a proximal device interface180 and/or a distal device interface 190 that can interconnect themedical device or stent 200 with the core member 160. The proximaldevice interface 180 can comprise a proximal engagement member 182 thatis configured to underlie the stent 200 and engage an inner wall of thestent. In this manner, the proximal engagement member 182 cooperateswith the overlying inner wall 118 of the catheter 110 to grip the stent200 such that the proximal engagement member 182 can move the stent 200along and within the catheter 110, e.g., as the user pushes the coremember 160 distally and/or pulls the core member proximally relative tothe catheter 110, resulting in a corresponding distal and/or proximalmovement of the stent 200 within the catheter lumen 116.

The proximal engagement member 182 can be fixed to the core member 160(e.g., to the distal wire 172 thereof in the depicted embodiment) so asto be immovable relative to the core member 160, either in alongitudinal/sliding manner or a radial/rotational manner.Alternatively, as depicted in FIGS. 1-8, the proximal engagement member182 can be coupled to (e.g., mounted on) the core member 160 so that theproximal engagement member 182 can rotate about the longitudinal axisA-A of the core member 160 (e.g., of the distal wire 172), and/or moveor slide longitudinally along the core member. In such embodiments, theproximal engagement member 182 can have an inner lumen that receives thecore member 160 therein such that the proximal engagement member 182 canslide and/or rotate relative to the core member 160. Additionally insuch embodiments, the proximal device interface 180 can further comprisea proximal restraint 184 that is fixed to the core member 160 andlocated proximal of the proximal engagement member 182, and/or a distalrestraint 186 that is fixed to the core member 160 and located distal ofthe proximal engagement member 182. The proximal and distal restraints184, 186 can be spaced apart along the core member 160 by a longitudinaldistance that is greater than the length of the proximal engagementmember, so as to leave one or more longitudinal gaps 187 between theproximal engagement member 182 and one or both of the proximal anddistal restraints 184, 186, depending on the position of the proximalengagement member between the restraints. When present, the longitudinalgap(s) 187 allow the proximal engagement member 182 to slidelongitudinally along the core member 160 between the restraints 184,186. The longitudinal range of motion of the proximal engagement member182 between the restraints 184, 186 is approximately equal to the totallength of the longitudinal gap(s) 187.

Instead of or in addition to the longitudinal gap(s) 187, the proximaldevice interface 180 can comprise a radial gap 188 (FIG. 3) between theouter surface of the core member 160 and the inner surface of theproximal engagement member 182. Such a radial gap 188 can be formed whenthe proximal engagement member 182 is constructed with an inner luminaldiameter that is somewhat larger than the outer diameter of thecorresponding portion of the core member 160. When present, the radialgap 188 allows the proximal engagement member 182 to rotate about thelongitudinal axis A-A of the core member 160 between the restraints 184,186. The presence of longitudinal gaps 187 of at least a minimal size oneither side of the proximal engagement member 182 can also facilitatethe rotatability of the proximal engagement member.

One or both of the proximal and distal restraints 184, 186 can have anoutside diameter or other radially outermost dimension that is smallerthan the outside diameter or other radially outermost dimension of theproximal engagement member 182, so that one or both of the restraints184, 186 will tend not to contact the inner surface of the stent 200during operation of the core assembly 140.

In the proximal device interface 180 shown in FIGS. 1-8, the stent 200can be moved distally or proximally within the catheter 100 via theproximal engagement member 182. During distal movement, the distal endof the proximal restraint 184 bears on the proximal end of theengagement member 182, and the engagement member urges the stent 200distally via frictional engagement with the inner surface of the stent200 (assisted by the overlying catheter 110). During proximal movement,the proximal end of the distal restraint 186 bears on the distal end ofthe engagement member 182, which in turn moves the stent 200 proximallyvia such frictional engagement. Proximal movement of the stent 200relative to the catheter 110 can be employed when withdrawing orre-sheathing the stent 200 back into the distal end 114 of the catheter110, as will be discussed in greater detail below. When the stent 200has been partially deployed and a portion of the stent remains disposedbetween the proximal engagement member 182 and the inner wall of thecatheter (see FIGS. 6, 7), the stent 200 can be withdrawn back into thedistal opening 120 of the catheter by moving the core assembly 140(including the engagement member 182) proximally relative to thecatheter 110 (and/or moving the catheter 110 distally relative to thecore assembly 140). Re-sheathing in this manner remains possible untilthe engagement member 182 and/or catheter 110 have been moved to a pointwhere the engagement member 182 is beyond the distal opening 120 of thecatheter 110 and the stent 200 is released from between the member 182and the catheter 110.

Optionally, the proximal edge of the proximal engagement member 182 canbe positioned just distal of the proximal edge of the stent 200 when inthe delivery configuration shown in FIGS. 1-5. In some such embodiments,this enables the stent 200 to be re-sheathed when as little as about 3mm of the stent remains in the catheter 110. Therefore, with stents 200of typical length, resheathability of 75% or more can be provided (i.e.the stent 200 can be re-sheathed when 75% or more of it has beendeployed).

The distal device interface 190 can comprise a distal engagement member192 that can take the form of, for example, a distal device cover ordistal stent cover (generically, a “distal cover”). The distal cover 192can be configured to reduce friction between the medical device or stent200 (e.g., the distal portion or distal end thereof) and the innersurface 118 of the catheter 110. For example, the distal cover 192 canbe configured as a lubricious, flexible structure having a free firstend or section 192 a that can extend over at least a portion of thestent 200 and/or intermediate portion 166 of the core assembly 160, anda fixed second end or section 192 b that can be coupled (directly orindirectly) to the core member 160.

The distal cover 192 can have a first or delivery position,configuration, or orientation (see, e.g., FIGS. 1-5) in which the distalcover can extend proximally relative to the distal tip 164, orproximally from the second section 192 b or its (direct or indirect)attachment to the core member 160, and at least partially surround orcover a distal portion of the stent 200. The distal cover 192 can bemovable from the first or delivery orientation to a second orresheathing position, configuration, or orientation (see, e.g., FIGS.7-8) in which the distal cover can be everted such that the first end192 a of the distal cover is positioned distally relative to the secondend 192 b of the distal cover 192 to enable the resheathing of the coreassembly 140, either with the stent 200 carried thereby, or without thestent.

The distal cover 192, particularly the first end 192 a thereof, cancomprise one or more flexible, generally longitudinally extendingstrips, wings, or elongate portions that are coupled to or integrallyformed with the second end 192 b. The distal cover 192 can bemanufactured or otherwise cut from a tube of the material selected forthe distal cover or from multiple radial portions of such a tube. Insuch embodiments the first section 192 a may be formed as multiplelongitudinal strips cut from the tube, and the second section 192 b maybe an uncut (or similarly cut) length of the tube. Accordingly, thesecond section 192 b and the proximally extending strips of the firstsection 192 a may form a single, integral device or structure. In someembodiments, the distal cover 192 comprises only one, or no more thantwo strips, wings, or elongate portions.

In some embodiments, the distal cover 192 may comprise a tube or alongitudinally slit tube, and the first section 192 a can include two ormore semi-cylindrical or partially cylindrical strips or tube portionsseparated by a corresponding number of generally parallel,longitudinally oriented cuts or separations formed or otherwisepositioned in the sidewall of the tube. Therefore, when in thepre-expansion state, as shown in FIGS. 1-5, the first section 192 a maygenerally have the shape of a longitudinally split or longitudinallyslotted tube extending or interposed radially between the outer surfaceof the stent or device 200 and the inner surface 118 of the catheter110.

In various embodiments, the strips, wings, or elongate portions of thefirst section 192 a may collectively span substantially the entirecircumference of the outer surface of the stent 200 (e.g., where thecuts between the strips are splits of substantially zero width), or besized somewhat less than the entire circumference (e.g., where the cutsbetween the strips are slots having a nonzero width). In accordance withsome embodiments, the width of the strips, wings, or elongate portionsof the first section 192 a can be between about 0.5 mm and about 4 mm.The width can be about 0.5 mm to about 1.5 mm. In accordance with someembodiments, the width can be about 1 mm.

The strips, wings, or elongate portions of the first section 192 a canalso extend longitudinally over at least a portion of the distal portionof the stent 200. In various embodiments, the first section 192 a canextend between about 1 mm and about 3 mm, or between about 1.5 mm andabout 2.5 mm, or about 2 mm, over the distal portion of the stent.

The first section 192 a and the second section 192 b can define a totallength of the distal cover 192. In some embodiments, the total lengthcan be between about 4 mm and about 10 mm. The total length can also bebetween about 5.5 mm and about 8.5 mm. In some embodiments, the totallength can be about 7 mm.

The strips of the first section 192 a may be of substantially uniformsize. For example, the first section 192 a can comprise two stripsspanning approximately 180 degrees each, three strips spanningapproximately 120 degrees each, four strips spanning approximately 90degrees each, or otherwise be divided to collectively cover all or partof the circumference of the stent, etc. Alternatively, the strips maydiffer in angular sizing and coverage area without departing from thescope of the disclosure. In one embodiment, only two strips or tubeportions are employed in the first section 192 a. The use of only twostrips can facilitate radial expansion, distal movement and/or fold-overor everting of the first section 192 a, as discussed herein, whileminimizing the number of free or uncontained strips in the blood vessellumen and any potential for injuring the vessel by virtue of contactbetween a strip and the vessel wall.

The distal cover 192 can be manufactured using a lubricious and/orhydrophilic material such as PTFE or Teflon®, but may be made from othersuitable lubricious materials or lubricious polymers. The distal covercan also comprise a radiopaque material which can be blended into themain material (e.g., PTFE) to impart radiopacity. The distal cover 192can have a thickness of between about 0.0005″ and about 0.003″. In someembodiments, the distal cover can be one or more strips of PTFE having athickness of about 0.001″.

The distal cover 192 (e.g., the second end 192 b thereof) can be fixedto the core member 160 (e.g., to the distal wire 172 or distal tip 164thereof) so as to be immovable relative to the core member 160, eitherin a longitudinal/sliding manner or a radial/rotational manner.Alternatively, as depicted in FIGS. 1-3 and 5-8, the distal cover 192(e.g., the second end 192 b thereof) can be coupled to (e.g., mountedon) the core member 160 so that the distal cover 192 can rotate aboutthe longitudinal axis A-A of the core member 160 (e.g., of the distalwire 172), and/or move or slide longitudinally along the core member. Insuch embodiments, the second end 192 b can have an inner lumen thatreceives the core member 160 therein such that the distal cover 192 canslide and/or rotate relative to the core member 160. Additionally insuch embodiments, the distal device interface 190 can further comprise aproximal restraint 194 that is fixed to the core member 160 and locatedproximal of the (second end 192 b of the) distal cover 192, and/or adistal restraint 196 that is fixed to the core member 160 and locateddistal of the (second end 192 b of the) distal cover 192. The proximaland distal restraints 194, 196 can be spaced apart along the core member160 by a longitudinal distance that is greater than the length of thesecond end 192 b, so as to leave one or more longitudinal gaps 197between the second end 192 b and one or both of the proximal and distalrestraints 194, 196, depending on the position of the second end 192 bbetween the restraints. When present, the longitudinal gap(s) 197 allowthe second end 192 b and/or distal cover 192 to slide longitudinallyalong the core member 160 between the restraints 194, 196. Thelongitudinal range of motion of the second end 192 b and/or distal cover192 between the restraints 194, 196 is approximately equal to the totallength of the longitudinal gap(s) 197.

Instead of or in addition to the longitudinal gap(s) 197, the distaldevice interface 190 can comprise a radial gap 198 between the outersurface of the core member 160 (e.g., of the distal wire 172) and theinner surface of the second end 192 b. Such a radial gap 198 can beformed when the second end 192 b is constructed with an inner luminaldiameter that is somewhat larger than the outer diameter of thecorresponding portion of the core member 160. When present, the radialgap 198 allows the distal cover 192 and/or second end 192 b to rotateabout the longitudinal axis A-A of the core member 160 between therestraints 194, 196. The presence of longitudinal gaps 197 of at least aminimal size on either side of the second end 192 b can also facilitatethe rotatability of the distal cover.

One or both of the proximal and distal restraints 194, 196 can have anoutside diameter or other radially outermost dimension that is smallerthan the (e.g., pre-deployment) outside diameter or other radiallyoutermost dimension of the distal cover 192, so that one or both of therestraints 194, 196 will tend not to bear against or contact the innersurface 118 of the catheter 110 during operation of the core assembly140.

In the embodiment depicted in FIGS. 1-3 and 5-8, the second end 192 b ofthe distal cover 192 includes an internal hoop 192 c which can comprisea (metallic or polymeric) coil as depicted, or other generally rigid,tubular or cylindrical internal member such as a short segment ofrelatively stiff polymeric or metallic tubing. The internal hoop 192 ccan be contained in an annular enclosure or loop(s) formed by the secondend 192 b, or otherwise attached to or integrated into the second end192 b in a manner that tends to maintain an inside diameter of thedistal cover 192 in the second end 192 b that is larger than the outsidediameter of the adjacent portion of the core member 160 (or the wire 172thereof). In other words, the hoop 192 c can help maintain the presenceof the radial gap 198 between the inside diameter of the second end 192b and the outside diameter of the core member 160 or distal wire 172.

The annular enclosure or loop(s) of the second end 192 b can be formedby wrapping a portion of a sheet or tube of the distal cover material(e.g., PTFE) around the sidewall and through the lumen of the hoop 192 cand adhering, gluing or heat bonding an end of the wrapped portion ofthe sheet or tube to the adjacent, proximally extending portion of thesheet or tube. Thus are formed two layers that are adhered together onthe proximal side of the hoop 192. Where the distal cover materialcomprises PTFE, unsintered PTFE can be used to enable bonding the twoportions of the material together with heat and pressure, which is nottypically possible with “ordinary” or sintered PTFE.

In operation, the distal cover 192, and in particular the first section192 a, can generally cover and protect the distal end 204 of the stent200 as the stent 200 is moved distally within the catheter 110. Thedistal cover 192 may serve as a bearing or buffer layer that, forexample, inhibits filament ends of the distal end 204 of the stent 200(where the stent 200 comprises a braided stent) from contacting theinner surface 118 of the catheter 110, which could damage the stent 200and/or catheter 110, or otherwise compromise the structural integrity ofthe stent 200. Since the distal cover 192 may be made of a lubriciousmaterial, the distal cover 192 may exhibit a low coefficient of frictionthat allows the distal end 204 of the stent 200 to slide axially withinthe catheter 110 with relative ease. The coefficient of friction betweenthe distal cover and the inner surface of the catheter can be betweenabout 0.02 and about 0.4. For example, in embodiments in which thedistal cover and the catheter are formed from PTFE, the coefficient offriction can be about 0.04. Such embodiments can advantageously improvethe ability of the core assembly to pass through the catheter,especially in tortuous vasculature.

Further, as shown in FIGS. 1-5, at least a portion of the distal cover192 can at least partially extend or be interposed radially between thedistal portion of the stent 200 and the inner surface 118 of thecatheter 110 in the first position, configuration, or orientation. Inthe first orientation, the first section 192 a of the distal cover 192can extend from the second section 192 b in a proximal direction to apoint where the first section is interposed between the distal portionof the stent 200 and the inner surface 118 of the catheter 110. In thisorientation, the first section of the distal cover can take on a“proximally oriented” position or configuration.

The core assembly 140 shown in FIGS. 1-4 can operate as illustrated inFIGS. 5-9. The core assembly 140 can be distally advanced until thedistal portion of the stent 200 is positioned distally beyond the distalend 114 of the catheter 110 to permit expansion of the distal portion ofthe stent 200 into a lumen 104 of the blood vessel 102. As the distalportion of the stent 200 expands, it can cause the distal cover 192 tobe opened or moved from the first orientation. Because (when braided)the stent 200 can often foreshorten as it expands, the stent 200 canwithdraw from engagement with the distal cover 192, as shown in FIG. 6.

After the distal cover 192 has become disengaged from the stent 200 toreach the state shown in FIG. 6, the cover can proceed to the secondorientation as shown in FIG. 7, as oncoming blood flow and/or otherforces urge the first section 192 a distally relative to the core member160. Alternatively, the distal cover 192 can remain substantially in thedisengaged, proximally-extending configuration shown in FIG. 6 until thecore assembly 140 is withdrawn proximally into the catheter 110, atwhich point the distal end 114 of the catheter 110 can force theapproaching first section 192 a of the cover 192 to evert or otherwisetake on the second configuration as shown in FIGS. 7-8. In each case,the distal cover 192 can move toward an everted position orconfiguration in which the first section 192 a of the distal cover 192is flipped, everted or rotated to extend in a distal direction or in a“distally oriented” position or configuration. In some embodiments of adistally-oriented second configuration, all or at least a portion of thefirst section 192 a is located distal of all or at least a portion ofthe second section 192 b.

The stent 200 can be further unsheathed and subsequently released intoposition in the lumen 104 of the vessel 102, e.g., across and/orspanning a neck 106 of an aneurysm 108 formed in the wall of the vessel102 (as shown in FIG. 9), or the stent 200 can be retracted andwithdrawn back into the catheter 110 (as shown in FIG. 8), if needed. Ineither situation, when the distal portion of the core assembly 140 iswithdrawn into the lumen 116 of the catheter 110, the distal cover 192can be retracted into the catheter 110 in the second position,configuration, or orientation, in which the distal cover 192 can be atleast partially everted, as shown in FIGS. 7 and 8. This can facilitatecomplete resheathing of the stent 200 and/or the core assembly 140within the catheter 110.

In some embodiments, in the first orientation, the first section 192 aof the distal cover 192 is positioned outside of a radial space 210located between the core assembly 160 or axis A-A (in either case distalof the second section 192 b or the location where the distal cover 192is connected to the core member) and the inner wall of the catheter 110,as shown in FIG. 3. The distal cover 192 can extend proximally from thesecond section 192 b and/or connection location, and away from theradial space 210. Additionally, in some such embodiments, in the secondorientation, some or all of the first section 192 a of the distal cover192 can extend distally through the radial space 210 upon retraction ofthe core assembly 140 into the catheter 110, as shown in FIG. 8.

Further, in some embodiments, the first section 192 a of the distalcover 192 can radially overlap with the distal end 204 of the stent 200at an overlap point 212 along the core member 160. As illustrated inFIG. 3, the overlap point 212 can be located along the core member 160at or near a distal end 214 of the intermediate portion 166 of the coremember 160, or at any location along the core member 160 that underliesan overlap of the (first section 192 a of the) distal cover 192 over thestent 200 when the core assembly 140 is in its pre-deploymentconfiguration shown in FIGS. 1-3 and 5. Additionally, in some suchembodiments, in the second orientation, the first section 192 a of thedistal cover 192 no longer overlaps with the (distal end 204 of) thestent 200 at the overlap point 212 (and the first section 192 a can belocated distally of such location), upon retraction of the core assembly140 into the catheter 110, as shown in FIG. 8.

In the second orientation, as shown in FIGS. 7-8, there is no longerradial overlap of the stent 200 and the cover 192 at the overlap point212 or at the distal end 214 of the intermediate section 166. Thus,after disengagement of the distal cover 192 from the stent 200, the coreassembly 140 can be proximally withdrawn into the catheter 110 and thedistal cover 192 can generally extend in a distal direction away fromthe overlap point 212. As also shown in FIG. 8, at such time that thestent 200 is resheathed or withdrawn into the catheter 110 after partialexpansion or deployment, the stent 200 and the distal cover 192 will notoverlap at the overlap point 212. Thus, the distal cover 192 will notoverlap the stent 200 or the overlap point 212 after at least partialexpansion of the stent 200 when the core assembly 140 is withdrawn intothe catheter 110. Further, once the distal cover 192 is disengaged, theintermediate portion 166 of the core member 160 can be positionedradially adjacent to the distal end 114 of the catheter 110 with thedistal cover 192 being positioned outside of the radial space betweenthe intermediate portion 166 and the (inner wall 118 of the) catheter110. Accordingly, the movement and configuration of the distal cover 192can enable the core assembly 140 to provide radial clearance between thecore member 160 or the intermediate portion 166 and the catheter 110 forfacilitating resheathing of the core member 160 and stent 200, as shownin FIGS. 7-8.

Structures other than the herein-described embodiments of the distalcover 192 may be used in the core assembly 140 and/or distal deviceinterface 190 to cover or otherwise interface with the distal end 204 ofthe stent 200. For example, a protective coil or other sleeve having alongitudinally oriented, proximally open lumen may be employed. Suitablesuch protective coils include those disclosed in U.S. Patent ApplicationPublication No. 2009/0318947 A1, published on Dec. 24, 2009, titledSYSTEM AND METHOD FOR DELIVERING AND DEPLOYING AN OCCLUDING DEVICEWITHIN A VESSEL.

In embodiments of the core assembly 140 that employ both a rotatableproximal engagement member 182 and a rotatable distal cover 192, thestent 200 can be rotatable with respect to the core member 160 about thelongitudinal axis A-A thereof, by virtue of the rotatable (connectionsof the) proximal engagement member 182 and distal cover 192. In suchembodiments, the stent 200, proximal engagement member 182 and distalcover 192 can rotate together in this manner about the core member. Whenthe stent 200 can rotate about the core member 160, the core assembly140 can be advanced more easily through tortuous vessels as the tendencyof the vessels to twist the stent and/or core assembly is negated by therotation of the stent, proximal engagement member and distal cover aboutthe core member. In addition, the required push force or delivery forceis reduced, as the user's input push force is not diverted into torsionof the stent and/or core member. The tendency of a twisted stent and/orcore member to untwist suddenly or “whip” upon exiting tortuosity ordeployment of the stent, and the tendency of a twisted stent to resistexpansion upon deployment, are also reduced or eliminated. Further, insome such embodiments of the core assembly 140, the user can “steer” thecore assembly 140 via the tip coil 165, particularly if the coil 165 isbent at an angle in its unstressed configuration. Such a coil tip can berotated about the axis A-A relative to the stent 200, engagement member182 and/or distal cover 192 by rotating the distal end 162 of the coremember 160. Thus the user can point the coil tip in the desireddirection of travel of the core assembly, and upon advancement of thecore assembly the tip will guide the core assembly in the chosendirection.

As noted, embodiments of the distal cover can provide variousadvantages. For example, the use of the distal cover can allow the coreassembly to be easily urged toward the treatment site within thecatheter. This can advantageously reduce the delivery force required tomove the core assembly through the catheter. Further, a flexible distalcover such as the depicted distal cover 192 can also allow the distalportion of the stent to open or expand radially immediately as thedistal portion of the stent exits the catheter. The distal cover can beeasily urged away from the first or encapsulating position orconfiguration such that the expansion of the stent is not hindered andexpansion can be predictable to the clinician. Where employed, this canbe a significant improvement over prior art devices that used arelatively rigid tube, such as a coil to distally restrain a distal endof the stent, which could impede or make unpredictable the properexpansion or deployment of the distal end of the stent.

Further, where the first portion 192 a is flexible, evertible, and/orprovides a minimal cross-section, the intermediate portion of the coreassembly can be easily recaptured within the catheter (with or withoutthe stent coupled thereto (e.g., mounted thereon)) to facilitateresheathing. Thus, the catheter can remain in place in the vasculatureand the entire core assembly can be withdrawn therefrom. This can enablethe clinician to “telescope” one or more other stents (e.g., deliveringmore than one stent such that it overlaps with another stent) withouthaving to remove the catheter, saving time and reducing trauma to thepatient. This also enables the clinician to remove the core assembly andstent entirely from the catheter in the event of a failure to deploy orother evident defect in the stent, and insert another core assembly andstent through the same catheter, with the same time savings andreduction in trauma.

In other embodiments, the distal device interface 190 can omit thedistal cover 192, or the distal cover can be replaced with a componentsimilar to the proximal engagement member 182. Where the distal cover192 is employed, it can be connected to the distal tip coil 165, e.g.,by being wrapped around and enclosing some or all of the winds of thecoil 165, or being adhered to or coupled to the outer surface of thecoil by an adhesive or a surrounding shrink tube. In still otherembodiments, the distal device interface 190 (or the proximal deviceinterface 180) can be omitted altogether.

Additional details regarding the proximal engagement member will now bediscussed, with reference especially to FIGS. 3, 10 and 11. Someembodiments of the proximal engagement member 182 can be of multi-layerconstruction, which can be useful for facilitating rotation of theengagement member 182 and/or stent 200 about the core member 160. Forexample, the proximal engagement member 182 can comprise a generallytubular or cylindrical inner layer 230, and another generally tubular orcylindrical outer layer 232 that overlies the inner layer 230. The outerlayer 232 can be adhered to or otherwise securely joined to the innerlayer 230 so that the two cannot rotate or move longitudinally relativeto each other during the ordinary use of the core assembly 140 anddelivery system 100.

The inner layer 230 and outer layer 232 can differ in mechanicalproperties such as hardness. For example, the outer layer 232 cancomprise a relatively soft material to facilitate relativelyhigh-friction or “high-grip” contact with the inner surface of the stent200. The inner layer can be formed from a relatively hard or stiffmaterial to facilitate low-friction engagement with the adjacent portionof the core member 160, and high hoop strength to resist inwarddeflection or collapse of the inner lumen 234 of the proximal engagementmember 182. Such inward deflection or collapse can result in “pinching”the core member 160 with the inner layer 230 and consequent degradationof the ability of the proximal engagement member 182 to rotate and/ormove longitudinally with respect to the core member 160. When contactdoes occur between the inner surface of the inner layer 230 and theouter surface of the core member 160, the relatively hard/stiff materialof the inner layer 230 minimizes the friction resulting from suchcontact.

In some embodiments of the multi-layer proximal engagement member, theouter layer 232 can be formed from a relatively soft polymer orelastomer such as silicone, rubber (e.g., Chronoprene™), thermoplasticpolyurethane (e.g., Tecoflex™) or polyether block amide (e.g., Pebax™).Whether made of such materials, or of other materials, the outer layer232 can have a durometer of between 10 A and 50 A, or between 15 A and40 A, or about 20 A, or about 25 A.

Instead of or in addition to the above-recited materials and/orproperties of the outer layer 232, in some embodiments, the inner layer230 can be formed from polyimide, e.g., a polyimide tube; alternativelya tubular metallic coil (e.g., a stainless steel coil) could beemployed, or a metal tube, either with or without slots or a spiral cutformed in the sidewall. Whether made of such materials, or of othermaterials, the inner layer 230 can have a higher durometer than theouter layer 232, e.g., above 70 D or between 70 D and 100 D.

In some embodiments, the inner and outer layers 230, 232 can beintegrally formed. For example, both layers could be formed from asingle cylinder of soft material wherein the harder/stiffer inner layercomprises the radially inner portions of the cylinder which have beentreated or processed to become harder/stiffer. Or the reverse could bedone, wherein a cylinder of hard material is processed to make its outerlayer softer and/or higher-friction.

Although, as disclosed above, the outer layer 232 can be made from avariety of materials, silicone is particularly preferred because itoffers a high coefficient of friction, high heat resistance tofacilitate sterilization, and high creep resistance to resist being“imprinted” with, or interlocked with, the filament or strut pattern ofthe adjacent medical device or stent 200. The high coefficient offriction of silicone also facilitates the use of a relatively shortproximal engagement member, e.g., (for delivery of a neurovascularstent) less than 5 mm, less than 3 mm, between 1 mm and 3 mm, or between2 mm and 2.5 mm. It is also preferred to use a silicone outer layer 232in combination with a thermoset material (such as polyimide) for theinner layer 230, of a higher durometer than the outer layer 232, orgenerally to use thermoset materials for both the inner and outer layers230, 232, with the outer layer of lower durometer than the inner layer.

Despite these advantages of silicone, it is difficult to process in amanner useful to form a multi-layer tubular component like the proximalengagement member 182, e.g., via co-extrusion. Because of thisdifficulty, it was necessary for the inventors to develop a method ofmanufacturing the proximal engagement member 182 with a silicone outerlayer 232 and an inner layer of higher-durometer thermoset material suchas polyimide.

In one embodiment, the proximal engagement member 182 can bemanufactured as follows. A length of polyimide tubing of approximately100 mm in length can be placed over a metallic mandrel so that themandrel passes through the lumen of the tubing. The mandrel is sized tofit closely within the tubing lumen so as to hold the tubing in place onthe mandrel via frictional engagement with the inner wall of the tubing.In addition, the close fit of the mandrel helps to seal the tubing lumenfrom inflow of silicone material during the subsequent dip coating ofthe tubing. Once the tubing is on the mandrel, the mandrel is mounted ona dipping fixture.

A silicone reservoir is provided in the form of a vertical, open-toppedcylinder, and the cylinder is prepared by wiping the inner surfaces ofit with 70% isopropyl alcohol and allowing it to dry for 5 minutes. Themounted polyimide tubing is prepared in a similar manner by wiping ittwice with a lint-free cloth wetted with 70% isopropyl alcohol andallowing it to dry for 5 minutes. Once the tubing is dry, it is“painted” with a primer (e.g., MED-163 Primer from NuSil Technology ofCarpinteria, Calif. USA) by first wetting the bristles of an applicatorbrush with a pipette full of the primer, and then painting the tubing(held along with the mandrel in a vertical orientation from the dippingfixture) with the wet brush with a bottom-to-top motion in a first pass,and then in a second pass after rotating the tubing and mandrel 90degrees about the vertical axis of the tubing and mandrel. Once theprimer has been applied to the tubing in this manner, the tubing isallowed to dry while exposed in a humidity chamber at 50%-70% relativehumidity and 23°-28° C. temperature for 30-45 minutes.

Flowable silicone material is prepared using, for example, a 2-partmedical silicone such as MED-4011 (Parts A and B) from NuSil Technologyof Carpinteria, Calif. USA. The silicone elastomer (Part A) and liquidcrosslinker (Part B) are combined in a mix of 10 parts elastomer with 1part crosslinker, and mixed in a sealed container in a centrifugal mixerat 3000 rpm for 60 seconds. After mixing, the silicone is allowed to sitfor ten minutes before the container is unsealed.

The flowable silicone is then poured into the reservoir cylinder, andthe reservoir is positioned in a programmable dipping apparatus beneatha vertically moveable dipping actuator. The dipping fixture, mandrel andtubing are mounted on the dipping actuator with the mandrel and tubingin a vertical, downward-extending orientation, and the vertical axis ofthe mandrel and tubing aligned with the central vertical axis of thereservoir cylinder. The dipping apparatus is then operated to lower thedipping actuator, mandrel and tubing to a position in which the lowerend of the tubing is just above the surface of the silicone. The tubingand mandrel are then lowered or dipped into the silicone substantiallyalong a straight line at a velocity of 2.29 mm per minute, over a strokedistance of 110 mm. At the bottom of the stroke, the dipping actuator,tubing and mandrel are raised out of the silicone at a velocity of 400mm/minute.

The fixture, mandrel and coated tubing are then removed from the dippingapparatus and placed in an oven at 100° C. temperature for 15 minutes.In the oven, the tubing and mandrel are oriented vertically but invertedrelative to their orientation employed during the dipping process. Afterremoval from the oven, the coated tubing is allowed to cool for 5minutes. After cooling, the tubing is sliced into individual proximalengagement members 182 with a series of cuts made along the tubingorthogonal to the longitudinal axis of the tubing.

In some embodiments, the proximal engagement member can have an axiallength of 2.25 mm, overall outside diameter of 0.02275-0.02500″, insidediameter of 0.010″, inner layer 230 thickness (e.g., polyimide tubingwall thickness) of 0.0015″, outer layer 232 thickness greater than0.003″, and inner layer 230 outside diameter of 0.0135″ or less.

The use of a “high-grip” material such as silicone for the outer layer232 makes practical the use of a proximal engagement member 182 that isrelatively short in axial length (i.e., the dimension measured along orparallel to the longitudinal axis A-A). The proximal engagement membercan be less than 5.0 mm in axial length, or less than 3.0 mm in axiallength, or between 1.3 mm and 5.0 mm in axial length, or between 1.3 mmand 3.0 mm in axial length. Generally, a shorter proximal engagementmember 182 is advantageous because shortness tends to reduce thetendency of the engagement member 182 to stiffen the core assembly 140and delivery system 100. Accordingly there is made possible in someembodiments an engagement member 182 that not only can rotate about thecore member 160 but can also effectively grip the inner surface of thestent 200 even at lengths below 5 mm, or below 3 mm.

As may be observed from FIGS. 10 and 11, the outer surface 236 of theouter layer 232 can comprise a generally smooth surface as shown in FIG.10, or a non-smooth surface such as that shown in FIG. 11, comprising,for example, a number of outwardly projecting and longitudinallyextending ridges 238 that alternate with longitudinally extendingrecesses 240. Other patterns of projecting members and recesses, such ascombinations of spikes and recessed portions, can also be employed.

With reference now to FIGS. 3, 4 and 12, it may be observed that thedistal restraint 186 of the proximal device interface 180, and/or theproximal and/or distal restraints 194, 196 of the distal deviceinterface 190, can each optionally comprise a tapered portion 250 and acylindrical or non-tapered portion 252. In the proximal device interface180, the distal restraint 186 can form a tapered portion 250 that islocated distal of its non-tapered portion 252, and tapers down indiameter or cross-sectional size as it extends distally, away from theproximal engagement member 182. In the distal device interface 190, theproximal restraint 194 can form a tapered portion 250 that is locatedproximal of its non-tapered portion 252, and tapers down in diameter orcross-sectional size as it extends proximally, away from the distalengagement member 192; the distal restraint 196 can form a taperedportion 250 that is located distal of its non-tapered portion 252, andtapers down in diameter or cross-sectional size as it extends distally,away from the distal engagement member 192. Accordingly, in the depictedembodiment each of the restraints 186, 194, 196 forms a tapered portion250 that tapers radially inwardly as it extends away from its respectiveengagement member 182/192 and/or its respective longitudinal gap (s)187/197.

By incorporating the tapered portion(s) 250, the restraint(s) 186, 194,196 can provide the benefit of relatively large diameter orcross-sectional size in the non-tapered portion 252 (effectivelongitudinal restraint of the engagement member 182/192) and/orrelatively long axial length (secure attachment to the core member 160)without suffering the drawback of increased stiffness or reducedbendability of the core assembly 140 and delivery system 100. This maybe understood best with reference to FIG. 12, which shows the deliverysystem 100 including the core assembly 140 passing through a bend in thevessel 102. In this drawing it can be observed that the tapered portion250 of the distal restraint 186 of the proximal device interface 180provides ample clearance for the sharply bending adjacent portion of thecatheter 110 and stent 200, as compared to a non-tapered restraint ofsimilar length and cross-sectional size or diameter. Accordingly thetapered restraint 186 allows the core assembly 140 and core member 160to bend more sharply (and/or to bend without the restraint contactingthe inner surface of the stent 200) in the vessel 102 than would bepossible with a non-tapered restraint of similar axial length andcross-sectional size or diameter. In this manner the risk of a distalcorner of the restraint 186 impinging on the inner surface of the stent200 and creating a pressure concentration that can require a higher pushforce from the user, is reduced.

With further reference to FIG. 3, in some embodiments the distalrestraint 196 of the distal device interface 190 may have a smaller(maximum) outside diameter or cross-sectional size than the proximalrestraint 194 of the distal interface 190. Such a smaller distalrestraint can help provide radial clearance for the everted first end192 a of the distal cover 192 during retraction into the catheter 110.

As seen in FIG. 13, in other embodiments, one, some or all of therestraints 184, 186, 194, 196 can comprise a tapered coil. Such coil(s)can be formed from wire stock with a tapering diameter; when wound intoa coil the resulting coil tapers to a smaller diameter in the smallerdiameter region of the wire. Restraints in the form of coils can providea high degree of flexibility and improve the bendability of the coreassembly 140 and delivery system 100.

One, some or all of the restraints 184, 186, 194, 196 can be formed froma radiopaque material (e.g., platinum, iridium, alloys thereof, etc.),so as to facilitate visibility of the respective portions of the coreassembly 140 in a patient via fluoroscopy or other imaging. In oneconfiguration, at least the distal restraint 186 of the proximal deviceinterface 180 is radiopaque, and the catheter 110 is radiopaque at ornear its distal tip, so as to indicate to the user that the proximalengagement member 182 is soon to exit the distal end of the catheter110, and the delivery system 100 or core assembly 140 as a result willlose the capability to withdraw the stent 200 back into the catheter110. Accordingly the user can observe via fluoroscopy that the distalrestraint 186 is approaching the distal end 114 of the catheter 110 andthereby recognize that the delivery system 100 or core assembly 140 willsoon lose the capability to withdraw the stent 200 back into thecatheter 110.

As mentioned previously, the core member 160 can optionally be ofmulti-member construction, and can include the tube 170 which cancomprise a hypotube. The tube 170 can have a sidewall that is “uncut” orwithout openings or voids formed therein. Alternatively, the tube 170can have openings, voids or cuts formed in the sidewall to enhance theflexibility of the tube. This may be done by cutting a series of slotsin the sidewall along part or all of the length of the tube, or cuttingor drilling a pattern of other openings in the sidewall, or cutting aspiral-shaped void in the sidewall.

In some embodiments, for example where the delivery system is to be usedin narrow and/tortuous vasculature, such as the neurovasculature, thetube 170 can be of relatively small outside diameter (e.g., 0.040″ orless, or 0.030″ or less, or 0.027″ or less, or about 0.020″); have arelatively thin sidewall thickness (e.g., 0.0050″ or less, or 0.0040″ orless, or about 0.0030″, or between 0.0025″ and 0.0035″); and/or be ofrelatively long overall length (e.g., 50 cm or more, or 60 cm or more,or 70 cm or more, or 80 cm or more, or about 91 cm). Instead of or inaddition to any one or combination of such dimensions, the tube can havea relatively long cut length (the length of the portion of the tube inwhich opening(s), void(s), cut(s), spiral(s) is/are present) of 50 cm ormore, or 60 cm or more, or 70 cm or more, or 80 cm or more, or about 86cm.

A relatively long, small-diameter and/or thin-walled spiral-cut tubeoffers certain advantages for use in the core member 160 in narrowand/tortuous vasculature, such as the neurovasculature. The tube can bemade highly flexible (or inflexible as the case may be) where necessaryby use of an appropriate spiral pitch, and the column strength or“pushability” of the tube can be maintained largely independent of itsflexibility, as the diameter of the tube can remain constant along itslength, in contrast with a long tapering wire which must sacrificepushability for flexibility as it narrows. The combination of highflexibility and pushability can facilitate easier navigation intodifficult, tortuous vascular locations.

Despite these advantages, difficulties can arise when attempting to makea relatively long, small-diameter and/or thin-walled spiral-cut tube.FIG. 14 illustrates some of these difficulties in the context of a lasercutting machine 300, in which the tube 170 is supported at one end in amoveable and rotatable chuck 302 and at the other end in a stationarybushing 304. A laser 306, also stationary, is positioned between thechuck 302 and the bushing 304 and oriented to emit a cutting laser beam308 at the sidewall of the tube 170 as the tube passes by the laser 308.The chuck 302 is programmable to rotate the tube 170 and move itlaterally relative to the laser beam 308 at selected rates of rotationand lateral movement, to form a spiral cut in the sidewall of the tubeat a desired pitch and location. The process begins with the chuck 302positioned at the maximum distance away from the laser 306 and bushing304 (with a maximum working length WL of tube 170 extendingtherebetween), and the chuck 302 and tube 170 coupled thereto movelaterally toward the laser 306 and bushing 304 while rotating until thechuck 302 reaches a minimum distance from the laser and bushing (with aminimum working length WL of tube 170 extending therebetween). However,when the working length WL of the tube 170 is long relative to itsdiameter and/or wall thickness, the tube 170 can sag as shown in FIG.14, and such sag can interfere with accurate cutting of a desired spiralpattern in the tube 170. Such a long working length WL can also lead totwisting of the tube 170 over the working length, as rotational frictionin the bushing 304 resists rotation of the tube 170 driven by the chuck302. The longer the working length WL, the more the tube tends to twistas a result of friction in the bushing 304. The resulting twisting of along tube 170 leads to torsional error in the spiral pattern cut by thelaser beam 308, which can be exacerbated as the torsion repeatedlybuilds up in the tube 170 and is released as the torsion periodicallyovercomes the friction in the bushing. In these circumstances, the tubenear the bushing 304 tends to rotate in “bursts” rather than at a steadyrate. Finally, at an overly long working length WL the tube 170 issusceptible to buckling as it is pushed toward the bushing 304 by thechuck 302.

In contrast, FIG. 15 shows the benefits of a relatively short workinglength WL: sag, torsional error and/or buckling can be reduced oreliminated altogether. However, the inventors discovered that at thedesired tube diameter and/or wall thickness the usable working length WLwas much smaller than the desired overall length or cut length (e.g., 50cm or more) of the tube 170. As an initial solution, the inventorsthought to form such a longer spiral by linking together a number ofseparate, longitudinally adjacent spirals that are cut individually overan acceptably short working length WL. For example, five separatelongitudinally adjacent cuts could be made, each at a working length ofabout 12 cm, in a “linked-together” fashion to form a long spiral cut ofabout 60 cm in length.

FIG. 16 illustrates a problem that arises when attempting to linktogether separate spirals. The depicted tube 170 includes a first spiral320 formed in the sidewall 322, and a second spiral 324 formed in thetube 170 and longitudinally adjacent to the first spiral 320. Eachspiral 320, 324 comprises a respective void 326, 328 in the sidewall 322that advances along the tube in a helical or spiraling form. The twospirals 320, 324 are longitudinally adjacent but not contiguous orcontinuous. Due to limitations in the laser cutting machine 300, theproximal end of the second spiral 324 cannot be positioned close enoughto the distal end of the first spiral 320 to make the two spiralscontiguous or continuous. Instead, the two spirals 320, 324 areseparated by a discontinuity 330 between the distal end of the firstspiral 320 and the proximal end of the second spiral 324. Such adiscontinuity can be a source of cracks formed in the sidewall 322 whenthe tube 170 is subject to bending, twisting or other stressesencountered in vascular use.

FIG. 17 illustrates one embodiment of a solution to the problems ofdiscontinuity and crack formation. In the embodiment of FIG. 17, the twospirals 320, 324 are formed in the same manner as in FIG. 16 but thespirals (and their respective voids 326, 328) are joined by a connectionaperture 332. The connection aperture 332 can comprise an additionalvoid that is formed (e.g., cut) in the sidewall 322 and is contiguous orcontinuous with the voids 326, 328 of the first and second spirals 320,324. Accordingly, the connection aperture 332 and the voids 326, 328 canbe considered to form a single, contiguous or continuous void extendingalong the contiguous or continuous first and second spirals 320, 324.The connection aperture 332 can comprise a circle, as shown in FIG. 17,or any other suitable shape such as an ellipse or polygon. A circle isthought to be advantageous due to a tendency to minimize the possibilityof crack formation near the juncture of the voids 326, 328.

In various embodiments of the tube 170, a relatively long contiguous orcontinuous helical or spiral cut can be provided in the sidewall of thetube. For example, the tube 170 can have such a helical or spiral cutover any of the various cut lengths specified above or elsewhere hereinfor the tube 170. A tube 170 having such a helical or spiral cut havealso have any one or combination of the various outside diameters,sidewall thicknesses and/or overall lengths specified above or elsewhereherein for the tube 170.

The long contiguous or continuous helical or spiral cut can beimplemented as discussed herein, e.g., as with respect to FIG. 17. Twoor more longitudinally adjacent spirals, cuts, slots or voids can beformed contiguously or continuously in the sidewall of the tube 170 andjoined at their adjacent ends by connection aperture(s) 332 to form aspiral or helical cut, slot or void that is contiguous or continuousalong the overall length or along the cut length of the tube 170. Insome embodiments, the individual spirals, cuts, slots or voids can beabout 15 cm in length, or 15 cm or less in length. These need not beuniform in length along the tube or cut length; for example the first orlast spiral, cut, slot or void can be made somewhat shorter in order toachieve a cut length that is not an even multiple of the length of theindividual spirals.

In some embodiments, one or more terminal apertures may be employed inthe spiral or helical cut, slot or void. Such terminal aperture(s) cansimilar to any of the connecting apertures 332 disclosed herein, withthe exception that they are positioned at one or both terminal ends ofthe spiral rather than at a juncture of two or more individual spirals.In still other embodiments of the tube 170, a spiral or helical cut,slot or void is employed with terminal aperture(s) at one or bothterminal ends and no connecting apertures along the cut length. One ormultiple such spirals may be formed in the sidewall 322 of a single tube170. Where employed, the terminal aperture(s) can serve as a stressrelief or measure against sidewall crack formation at the end(s) of thespiral. One example of a terminal aperture 334 can be seen in FIGS. 1-2and 5-8.

Instead of or in addition to a spiral that is contiguous or continuousover a relatively long overall length or cut length of the tube 170, thepitch of the spiral can be controlled precisely over a long overalllength or cut length. For example, the pitch of the spiral can vary overthe cut length such that a pitch of a specific magnitude can prevailalong a relatively short segment of the cut length, for example 5 mm orless, or 3 mm or less, or 2 mm or less, or about 1.0 mm. In this manner,the spiral pitch can be finely adjusted in small increments of the cutlength thereby facilitating superior control over the mechanicalproperties of the tube 170 (e.g., bending stiffness, column strength) invarious portions of the tube. Therefore, the tube 170 can have a pitchthat varies in magnitude (including a specific “first pitch magnitude”)along the overall length or cut length of the tube, and the first pitchmagnitude can prevail along a first segment of the cut length. The firstsegment can have a length (measured along the axis A-A) of 5 mm or less,or 3 mm or less, or 2 mm or less, or about 1.0 mm. The magnitude of thepitch can change from the first magnitude at one or both ends of thefirst segment. The first segment can be located (e.g., in a contiguousor continuous void) anywhere along the cut length, including location(s)relatively far from the endpoints of the cut length, e.g., more than 10cm away, or more than 20 cm away, or more than 30 cm away from anendpoint of the cut length.

Instead of or in addition to achievement of a particular pitch magnitudein one or more short segments of the cut length (and/or a spiral that iscontiguous or continuous over a relatively long overall length or cutlength of the tube 170), the pitch magnitude can be controlled preciselyso that it can vary in relatively small increments. (The pitch can beexpressed in mm/rotation.) For example, the pitch can vary in magnitudeby 0.2 mm/rotation or less, or 0.1 mm/rotation or less, or 0.01mm/rotation or less, or 0.005 mm/rotation or less. Thus is providedanother manner in which the spiral can be finely controlled tofacilitate desired mechanical properties in various portions of the tube170. Therefore, the tube 170 can have a pitch that varies in magnitude(including a specific “first pitch magnitude”) along the overall lengthor cut length of the tube, and the first pitch magnitude can prevailalong a first segment of the cut length. The magnitude of the pitch canchange from the first magnitude by 0.2 mm/rotation or less, or 0.1mm/rotation or less, or 0.01 mm/rotation or less, or 0.005 mm/rotationor less, at one or both ends of the first segment. The first segment canbe located (e.g., in a contiguous or continuous void) anywhere along thecut length, including location(s) relatively far from the endpoints ofthe cut length, e.g., more than 10 cm away, or more than 20 cm away, ormore than 30 cm away from an endpoint of the cut length.

In one embodiment, the tube 170 has an overall length of 91 cm, cutlength of 86 cm, outside diameter of 0.020″, wall thickness of 0.003″,spiral cut (slot) width of 25 microns, circular connection apertureswith a diameter of 100 microns, and individual spiral cut lengths ofabout 15 cm.

FIG. 18 depicts in flowchart form one embodiment of a method 350 offorming a relatively long spiral cut in the sidewall 322 of the tube170, using equipment such as the laser cutting machine 300 describedherein with reference to FIGS. 14-15. The method 350 begins at 352 bygripping the tube 170 with a rotating tool such as the chuck 302,followed at 354 by aligning or aiming the laser 306 with or at a portionof the tube 170, such as one of the proximal and distal ends thereof.Next, at 356 rotation and axial (lateral) advancement of the tube 170relative to the laser 306 is commenced, at rates selected to obtain thedesired spiral pitch, with the rotating tool or chuck 302. In thismanner the laser 306 begins to cut a helical or spiral void in thesidewall of the tube 170. This is continued 358 until the void has beenformed along the desired spiral segment length (e.g., 15 cm, or 15 cm orless). At 360, once the terminal end of the spiral segment has beenformed, the rotating tool or chuck 302 (and/or the laser 306) isoperated so as to form the connecting aperture 332 at the terminal endand contiguous or continuous with the just-formed spiral void. Then at362 the tube 170 is secured in place relative to the laser 306 andbushing 304 via for example a selectively actuatable tube grip that canbe incorporated into the bushing 304 or elsewhere in the machine 300,while the chuck 302 releases its grip on the tube 170 and retractslaterally away from the laser 306 and bushing 304 to the home position.Once in the home position, the chuck 302 grips the tube 170 once againand the actuatable tube grip releases the tube. At 364, the chuck 302and/or laser 306 is operated to aim or align the laser at or with theaperture 332. Once the laser 306 is so aimed or aligned, the chuck orrotating tool can be operated again as in 356 to rotate and laterallyadvance the tube 170 relative to the laser 306. Thus the laser 306begins to cut another spiral segment in the tube sidewall. Because ofthe initial positioning of the laser beam 308 in the aperture 332, thenew spiral segment begins at the perimeter of the aperture and the newsegment is contiguous or continuous with the aperture 332 and theprevious segment. As indicated in 368, acts 358-366 can now be repeateduntil the desired number of spiral segments and connecting apertures 332are formed, over a desired cut length of the tube 170.

FIGS. 19-20 show a vascular access route 400 that can be employed insome embodiments of methods of using the delivery system 100,particularly in such methods of using the delivery system 100 to delivera medical device or the stent 200 to the neurovasculature. The route 400can begin with percutaneous access into one of the femoral arteries 402and then proceed to the abdominal aorta 404 and to the aortic arch 406.From the aortic arch 406 the route 400 can proceed up to and through theneck 408 through (A) the brachiocephalic artery 410 and (i) right commoncarotid artery 412 or (ii) right vertebral artery 414, or (B) the leftcommon carotid artery 416, or (C) the left subclavian artery 418 andleft vertebral artery (not shown). When the route 400 passes through the(right) common carotid artery 412 it can then proceed past the (right)carotid bifurcation 420 into the (right) internal carotid artery (ICA)422. (The ICA commonly displays high tortuosity as shown at 424.) At theend of the ICA the route 400 can continue into one of the ICA's terminalbranches, the middle cerebral artery (MCA) 426 or the anterior cerebralartery (ACA) 428. In the MCA 426 the route 400 can proceed through theM1 segment, to or beyond the M1 bifurcation 430.

When the route 400 passes through the (right) vertebral artery 414, itfrequently encounters vertebral tortuosity such as shown at 432. Fromeither vertebral artery, the route 400 can proceed through the basilarartery (not shown) to or past the basilar tip, posterior cerebralarteries (not shown), or posterior communicating arteries (not shown).

Instead of beginning at access via the femoral artery 402, the route 400may begin at access via the left 418 or right 434 subclavian artery andproceed into the aortic arch 406, right common carotid artery 412 orright vertebral artery 414, and beyond as described above.

As seen in FIG. 19, the various embodiments of the vascular access route400 may be divided into up to four zones: Zone 1, characterized by therelatively straight, large-diameter femoral artery 402 and abdominalaorta 404; Zone 2, including the sharply turning aortic arch 406 and itsjunctions with the arteries branching from the arch 406 toward the neck408; Zone 3, with the common carotid and proximal vertebral arteries,and proximal ICA; and Zone 4, characterized by highly tortuous segmentsof the ICA 422 or vertebral artery 414, and/or smaller-diameter vesselsthat are frequently tortuous, such as the MCA 426 and leading up to orbeyond the M1 bifurcation 430.

In some embodiments, the tube 170 can comprise a spiral-cut tube and thepitch of the spiral can vary along the overall length and/or cut lengthof the tube. The pitch can vary at a constant rate, or a non-constantrate. One or more segments of the cut length can have constant pitch,and these can be combined with one or more segments that have varyingpitch. The tube 170 can incorporate spiral-cut and non-spiral-cutportions.

In some embodiments, the cut portion of the tube 170 can have two ormore segments wherein the pitch is substantially constant (e.g., toimpart mechanical properties suited to a desired one of the Zonesindicated in FIG. 19) and these constant-pitch segments can be joined bysegments in which the pitch varies. For example, a proximal segment mayhave a relatively high substantially constant pitch (in mm/rotation) tomake the tube 170 relatively stiff in that segment, and a distal segmentmay have a relatively low substantially constant pitch (in mm/rotation)to make the tube 170 relatively flexible in that segment. These twosegments may be joined by a varying-pitch segment in which the pitch isgradually reduced from that of the proximal segment to that of thedistal segment. In this manner the tube 170 can incorporate a stiffproximal section for pushability and column strength, and a flexibledistal section for navigability in tortuous vessels. The tube 170 canaccommodate a relatively large change in pitch and stiffness between theproximal segment and the distal segment by making the change in pitchsufficiently gradual along the length of the varying-pitch segment. Thiscan be done by incorporating a sufficient number of pitch transitionsalong the length of the varying-pitch segment. The number of pitchtransitions per unit length of the tube can be considered a pitchtransition density or PTD.

If, in a varying-pitch segment positioned between two segments thatdiffer significantly in pitch or stiffness, the PTD is too low, thechange in pitch/stiffness at any individual pitch transition will berelatively high; as a result the tube 170 may have an unduly hightendency to kink at such an individual pitch transition as the tube isadvanced through a tortuous vessel and/or a high push force is exertedon the tube. In other words, if the tube incorporates an abrupttransition from a high-stiffness section to a low-stiffness section, thetube may be likely to kink at the transition point or segment whenencountering a sharp turn in a vessel and/or application of a high pushforce.

Therefore, in order to accommodate in the tube 170 multiple segmentsthat differ significantly in pitch/stiffness (and for example therebytailor the mechanical properties of the tube segments to the variousanatomical regions of the access route 400), without unduly increasingthe tendency of the tube to kink, it can be useful to employvarying-pitch segments or transition zones that have a relatively highPTD or a relatively high overall number N of transitions. When the tubeis forced to bend at or near a transition zone characterized bysufficiently high PTD and/or sufficiently high N, the bend becomes“spread” among the individual transitions in the transition zone,resulting in a gradual, arcing bend rather than a sudden, sharp kink.

FIG. 21 illustrates a varying pitch that may be used in some embodimentsof the tube 170. The tube 170 may incorporate one or more multiplesegments or flex zones of substantially or relatively constant pitch orstiffness, such as one, some or all of the zones Z1, Z2, Z3 (which caninclude two smaller zones Z3A, Z3B), and/or Z4 (which can include twosmaller zones Z4A, Z4B). The flex zones can decrease in pitch/stiffnessas the tube extends distally, e.g., with Z1>Z2>Z3>Z4 in pitch and/orstiffness. The zone Z1 can have a pitch and/or stiffness that issufficiently flexible for navigation in Zone 1 of the access route 400(FIG. 19), through the femoral artery 402 and abdominal aorta 404, whileretaining pushability and column strength to move the distal portions ofthe core assembly 140 through Zones 2, 3 and 4. The zone Z2 can have apitch and/or stiffness that is sufficiently flexible for navigation inZone 2 of the access route 400, particularly across the aortic arch andmaking a turn from the arch and extending into the one of the arteriesleading to the neck (brachiocephalic 410, left common carotid 418 orleft subclavian 418). The zone Z3 can have a pitch and/or stiffness thatis sufficiently flexible for navigation in Zone 3 of the access route400, particularly in the common carotid artery 412, or proximal portionsof the internal carotid artery 422 or vertebral artery 414. The zone Z4can have a pitch and/or stiffness that is sufficiently flexible fornavigation in Zone 4 of the access route 400, particularly in thetortuous distal portions of the internal carotid artery 422 (such as thecarotid siphon) and vertebral artery 414, and/or the middle cerebralartery 426 to the M1 bifurcation 430.

The flex zones Z1, Z2, Z3, Z4 can vary significantly relative to eachother in pitch and/or stiffness in order to accommodate their respectivetarget anatomies. For example, the zone Z4 can have a bending stiffnessless than 5%, or less than 3%, or less than 2%, or less than 1% of thebending stiffness of the tube 170 when uncut. The zone Z3 can have abending stiffness (A) greater than 8%, or greater than 10%, or greaterthan 12% of the bending stiffness of the tube 170 when uncut; and/or (B)less than 22%, or less than 20%, or less than 18%, or less than 17% ofthe bending stiffness of the tube 170 when uncut. The zone Z2 can have abending stiffness (A) greater than 27%, or greater than 29%, or greaterthan 30% of the bending stiffness of the tube 170 when uncut; and/or (B)less than 36%, or less than 34%, or less than 33% of the bendingstiffness of the tube 170 when uncut. The zone Z1 can have a bendingstiffness (A) greater than 38%, or greater than 40%, or greater than 42%of the bending stiffness of the tube 170 when uncut; and/or (B) lessthan 50%, or less than 46%, or less than 44% of the bending stiffness ofthe tube 170 when uncut. The foregoing bending stiffness values andranges can be implemented with reference to a tube 170 of any dimensionsdisclosed herein, including but not limited to a tube 170 having anoutside diameter of 0.040″ or less and/or a wall thickness of 0.010″ orless. Such a tube may be constructed from materials including polymers,and metals including nitinol and stainless steels such as 304 or 304Lstainless steel. One suitable tube 170 is constructed from 304Lstainless steel with an outside diameter of 0.020″ and a wall thicknessof 0.003″.

Instead of or in addition to the bending stiffnesses specified above,the zones Z1, Z2, Z3 and/or Z4 can have one, some or all of thefollowing bending stiffnesses in Newtons times millimeters squared(N*mmA2): Z4, less than 12, less than 10, less than 8, or about 5; Z3B,60-100, or 70-90, or about 80; Z3A, 90-130, 100-120, or about 110; Z2,180-220, 190-210, or about 205; and/or Z1, greater than 250, greaterthan 270, or about 280, or 250-310, or 270-290. The uncut tube 170 canhave a stiffness of 600-700, 625-675, or about 650. The foregoingbending stiffness values and ranges can optionally be normalized (toaccount for any differences in measuring equipment) with reference to avalue of 340 N*mmA2 for 0.017″ diameter solid wire made from 304stainless steel.

One, some or all of transition zones T1, T2, T3A and/or T3B canoptionally be provided to incorporate these differences inpitch/stiffness while minimizing any resulting tendency of the tube tokink between the flex zones. The transition zones T1, T2, T3A and/or T3Bcan have relatively high PTD or N, as discussed above. For example, thetransition zone T1 can have a PTD greater than 1.0 transitions percentimeter (T/cm), or of 2.0 T/cm or greater, or of about 2.0 T/cm; thetransition zone T2 can have a PTD greater than 0.5 T/cm, or of 0.74 T/cmor greater, or of about 0.74 T/cm; the transition zone T3A can have aPTD greater than 1.5 T/cm, or of 2.2 T/cm or greater, or of about 2.2T/cm; the transition zone T3B can have a PTD greater than 1.0 T/cm, orof 1.8 T/cm or greater, or of about 1.8 T/cm; and the transition zone T4can have a PTD greater than 6.0 T/cm, or of 8.9 T/cm or greater, or ofabout 8.9 T/cm.

The transition zone T3B can provide a transition in flexibility from therelatively soft zone Z4, which can have a bending stiffness (such as anyof those discussed above for Z4) suitable for navigating the distal ICAand M1 segment of the MCA, up to the stiffer zone Z3. Along thetransition zone T3B, the pitch can increase significantly from the pitchemployed in the zone Z4, by over 150%, over 200%, over 250%, or about254%, to the pitch employed in zone Z3. The transition zone T3B cancomprise a number of individual pitch transitions, such that the averageoverall percent increase in pitch achieved per individual transition is15% or less, or 12% or less, or 11% or less, or 10.5% or less, or about10.1%. (Such an average is computed by dividing the total percentincrease in pitch achieved in the transition zone by the total number oftransitions in the zone.) Instead of or in addition to any of theseaverages, the transition zone T3B can achieve a reduction in stiffnessof greater than 75%, or greater than 85%, or greater than 90%, or about94.5%, from the zone Z3 (particularly Z3B) to the zone Z4.

The transition zone T2 can provide a transition in flexibility from thezone Z3, which can have a bending stiffness (such as any of thosediscussed above for Z3) suitable for navigating the common carotidartery, proximal internal carotid artery, and/or proximal vertebralartery, to the stiffer zone Z2 which can have a stiffness (such as anyof those discussed above for Z2) suited to crossing the aortic archand/or extending into one of the arteries leading from the arch towardthe neck. Along the transition zone T2, the pitch can increasesignificantly from the pitch employed in the zone Z3, by over 80%, over100%, over 120%, or about 125%, to the pitch employed in zone Z2. Thetransition zone T2 can comprise a number of individual pitchtransitions, such that the average overall percent increase in pitchachieved per individual transition is 20% or less, or 15% or less, or13% or less, or about 12.5%. (Such an average is computed by dividingthe total percent increase in pitch achieved in the transition zone bythe total number of transitions in the zone.) Instead of or in additionto any of these averages, the transition zone T2 can achieve a reductionin stiffness of greater than 35%, or greater than 40%, or greater than45%, or about 47%, from the zone Z2 to the zone Z3.

The transition zone T1 can provide a transition in flexibility from thezone Z2, to the stiffer zone Z1 which can have a stiffness (such as anyof those discussed above for Z1) suited to passing through the femoralartery and abdominal aorta, and providing pushability for the moredistal portions of the core assembly 140. Along the transition zone T1,the pitch can increase significantly from the pitch employed in the zoneZ2, by over 35%, over 40%, or about 45%, to the pitch employed in zoneZ1. The transition zone T1 can comprise a number of individual pitchtransitions, such that the average overall percent increase in pitchachieved per individual transition is 10% or less, or 8% or less, or 6%or less, or about 5.6%. (Such an average is computed by dividing thetotal percent increase in pitch achieved in the transition zone by thetotal number of transitions in the zone.) Instead of or in addition toany of these averages, the transition zone T1 can achieve a reduction instiffness of greater than 15%, or greater than 20%, or greater than 25%,or about 27%, from the zone Z1 to the zone Z2.

Some, one or all flex zones Z1, Z2, Z3, Z4 can have a length greaterthan 30 mm, or greater than 40 mm. For example, the zone Z4 can have alength of 60 mm or more, or 80 mm or more, or 80-120 mm, or about 100mm. The zone Z3B can have a length of 40-60 mm, or about 50 mm and thezone Z3A can have a length of 50-70 mm, or about 60 mm. The zone Z2 canhave a length greater than 200 mm, or 200-300 mm, or 225-275 mm, orabout 250 mm. The zone Z1 can have a length of 50-70 mm, or about 60 mm.

Instead of or in addition to any one or combination of the lengthsspecified above, the zones can be situated along the tube 170 with theirrespective distal ends located at the following distances from thedistal end of the tube, or from the proximal end of the stent 200: Z4,8-12 mm, or about 10 mm; Z3B, 225-275 mm, or 240-260 mm, or about 250mm; Z3A, 300-340 mm, or 310-330 mm, or about 320 mm; Z2, 480-540 mm,490-530 mm, or about 515 mm; and/or Z1, 780-820 mm, or 790-810 mm, orabout 800 mm. By employing these locations along the tube, the zones Z1,Z2, Z3 and/or Z4 can be configured to occupy the anatomical regionsdescribed herein as corresponding to such region(s) when the distal endof zone Z4 or the intermediate region 166 is located within the M1segment of the MCA.

The tube 170 can optionally include a transition zone T4 at the distalend of the cut length, e.g., distal of and adjacent to the zone Z4. Thetransition zone T4 can be configured to serve a “steering” function topoint the tube 170 in the direction of travel of the distal portions ofthe core member 160 (e.g., distal wire 172) as those distal portionsnavigate turns within the vasculature. Accordingly the zone T4 can havea relatively high PTD (e.g., over 5 T/cm, over 7 T/cm, or about 9 T/cm),a relatively short length (e.g., less than 15 mm, or less than 12 mm, or8-10 mm, or about 9 mm), and/or an average stiffness less than thestiffness of the zone Z4 (e.g., a stiffness that decreases from that ofzone Z4 as zone T4 extends distally).

Numerous parameters for various aspects of a spiral cut of the tube 170are specified above. The scope of the present disclosure includes anysingle one or any combination of any number of the specified parameters.No one parameter, and no one value of any such parameter, should beregarded as essential.

Referring now to FIGS. 22-25, in some embodiments, the core assembly 140(and optionally together with the stent 200 or medical device carriedthereby) can be packaged in, or pre-loaded in an introducer sheath 450to thereby form a pre-load assembly 460. Such a pre-load assembly 460and introducer sheath 450 can facilitate rapid transfer of the coreassembly 140 and stent 200 into the catheter 110 via the hub 122 and/orproximal end 112. This can enable, for example, the catheter 110 to beselected independently of the core assembly 140 and stent 200. The coreassembly 140 and stent 200 can be packaged in a pre-loaded condition inthe introducer sheath 450 (e.g., with the resulting pre-load assembly ina coiled configuration), and the introducer sheath connected to theproximal end of the catheter 110 to enable delivery of the stent 200 viathe catheter 110. The introducer sheath can have an inside diameter thatis approximately equal to the inside diameter of the catheter 110, and atapered distal tip (not shown) to facilitate connection with theproximal end of the catheter 110.

As seen in FIGS. 22-25, after connection of the distal end of theintroducer sheath 450 to the proximal end 112 of the catheter 110, thepre-load assembly 460 and catheter 110 are in the state shown in FIGS.22-23, in which the core assembly 140 and stent are inside the sheath450, proximal of the catheter 110. From this state the core assembly 140and stent 200 can be advanced into the catheter 110 by gripping theexposed portion of the core member 160 proximal of the sheath 450, andpushing the core assembly 140 distally, thereby reaching the state shownin FIG. 24, with the stent 200 and much of the core assembly now locatedin the catheter 110. At this point the introducer sheath 450 can bedisconnected from the catheter 110 and refracted over the proximalportion of the core member 160, either to expose a portion of the coremember proximal of the catheter 110, or retracted entirely from the coremember 160 and discarded. FIG. 25 shows the result of completeretraction of the sheath 450; a portion of the core member 160 isexposed for gripping proximal of the proximal end of the catheter 110.The user can then grip the core member 160 there and push the coreassembly 140 and stent 200 further distally into the catheter 110 toproceed with delivery and/or deployment of the stent according to any ofthe methods disclosed herein.

The introducer sheath 450 can be made relatively long, e.g., 80 cm ormore, or 90 cm or more, or 100 cm or more, or about 106 cm.Alternatively, the introducer sheath 450 can have a length equal to orlonger than the length of the core assembly 140 from the distal tip tothe proximal end of the cut length of the tube 170. As still anotheralternative, the length of the introducer sheath 450 can be sufficientto cover the entire length of the core assembly 140 from its distal tipextending proximally, except for a proximal grip region 462 of the coremember 160 that is at or near the full insertable diameter of the coremember 160 and is at or near full stiffness (e.g., lacks significantflexibility enhancements such as a spiral cut or a pattern of slots orother openings formed or cut in the sidewall of a tube, or lackssignificant tapering in the case of a wire). In the case of the coreassembly 140 shown in FIGS. 1-8, the exposed proximal grip region cancomprise the proximal wire 168 and/or an uncut portion of the tube 170.

An introducer sheath of such length advantageously prevents the userfrom gripping or pushing on any of the “soft” or highly flexibleportions of the core assembly 140 or core member 160 when advancing thecore assembly 140 and stent 200 into the catheter 110, thus protectingsuch soft/flexible portions from damage. In addition, the introducersheath 450 helps resist buckling or kinking of the core member 160 whilethe core assembly 140 is being pushed into the catheter 110 via the gripregion 462, by constraining the amount to which the core member 160 canbend sideways under a compressive load.

As may be observed in FIGS. 23-25, before advancement of the coreassembly 140 and stent 200 distally from the sheath 450 into thecatheter 110, the sheath 450 covers the entire core assembly 140 andcore member 160 except for the proximal grip region 462. The user istherefore forced to grip the core member 160 in the proximal grip region462 to advance it into the catheter 110 (and/or prevented from graspingthe core member 160 anywhere else). After reaching the state shown inFIG. 24, the proximal grip region 462 is still the only exposed portionof the core assembly 140, although a smaller portion of the region 462is now exposed. (Optionally, the sheath 450 and core member 160/proximalwire 168 can be sized so that the proximal end of the core member 160 isflush with the proximal end of the sheath 450 upon reaching the stateshown in FIG. 24, or any similar state wherein the stent 200 is proximalof the distal end 114 of the catheter 110.) After partial or completeretraction of the introducer sheath 450 (FIG. 25), the proximal gripregion 462 is again the only portion of the core assembly 140 and coremember 160 that is exposed proximal of the catheter 110. Again the usercan grip the core member 160 only in the proximal grip region whilepushing the core assembly 140 distally into the catheter 110.

Instead of or in addition to the length(s) specified above, theintroducer sheath can have a sidewall which is translucent and/orcontrast-enhancing. For example, the sidewall can be of a translucentwhite or translucent yellow color (as opposed to clear or transparent).Optionally, a translucent white sidewall can be made by includingtitanium dioxide in the material or polymer used for forming the sheath450. With a translucent and/or contrast-enhancing sidewall, thefluorosafe marker(s) 176 can be made black in color, such as via surfaceoxidation of the proximal wire 168 with a laser or other heat treatment.

The translucent and/or contrast-enhancing sheath 450 can enhancevisibility of the fluorosafe marker 176, in a manner superior to atransparent sheath 450, during advancement of the core assembly 140(particularly when the sheath lumen contains a liquid such as saline) asshown in FIGS. 23-25. Prior to advancement of the core assembly 140(FIG. 23), the fluorosafe marker 176 can be located proximal of thesheath 450, or in a proximal portion of the sheath 450. As the coreassembly 140 and core member 160 are advanced into the catheter 110, thefluorosafe marker 176 is visible through the sidewall of the sheath 450so that the user can observe the movement of the fluorosafe marker 176within the sheath 450 until it reaches a position near the proximal endof the catheter (FIGS. 24, 25), thereby signaling to the user that thedistal end of the stent 200 is about to exit the distal end 114 of thecatheter 110. Recognizing this, the user can stop advancement of thecore assembly 140 until ready to move further and deploy the stent 200.If the proximal end of the core member 160 reaches the proximal end ofthe sheath 450 before the fluorosafe marker 176 and stent 200 reachtheir positions shown in FIG. 24, the user can nonetheless note theposition of the fluorosafe marker 176 through the sidewall of the sheath450, to enable the user to find the marker 176 upon refraction and/orremoval of the sheath 450. After retraction/removal of the sheath 450,the user can further advance the core member 140 distally (if necessary)to reach the state shown in FIG. 25, in which the fluorosafe marker 176is just proximal of the proximal end 112 of the catheter 110 and thedistal end of the stent is just proximal of the distal end 114 of thecatheter 110. By observing the position of the fluorosafe marker 176,the user recognizes that the stent is soon to emerge from the distal end114 of the catheter 110, and that it is now appropriate to activatefluoroscopic imaging to observe deployment of the stent into a bloodvessel via such imaging. Heretofore during some or all of theadvancement of the core assembly 140, the imaging had been keptdeactivated to minimize patient exposure to radiation.

FIG. 26 shows an additional embodiment of the core assembly 140 (withthe stent 200) which can be identical in structure, function andmethod(s) of use to any of the other embodiments of the core assembly140 described herein, except as further described as follows. In thisembodiment, the proximal device interface 180 (including for example theproximal engagement member 182 and/or its restraints 184, 186) can belocated in a distal portion of the stent 200, e.g., in the distal halfof the stent 200, overlapping with or just proximal of the distal cover192, or partially or wholly overlapping with the distal cover 192.Further, according to some embodiments, that the proximal deviceinterface 180 be located only in the distal half of the stent 200 doesnot mean that the proximal device interface 180 extends along the entiredistal half, but instead can refer to embodiments in which the proximaldevice interface extends along less than the distal half.

For example, the proximal engagement member 182 can be located so thatits distal end is less than 1 mm proximal of the proximal end of thecover 192, or distal of such location. With the proximal deviceinterface 180 and proximal engagement member 182 so located, the member182 can urge the stent 200 distally primarily by “pulling” the stentfrom a distal portion thereof, applying force to a point or region in adistal portion, or near the distal end, of the stent. When moving orpulling the stent in this fashion, the amount of push force necessary tobe exerted through the core member 160 is reduced because the tendencyof the stent to expand radially (as can occur when it is pushed distallyand longitudinally compressed by a force applied to a point or regionnear the proximal end of the stent) is reduced. Optionally, in theembodiment of FIG. 26 there may be no additional structures proximal ofthe engagement member 182 and/or interface 180 that transmit force fromthe core member 160 or wire 172 to the stent 200.

FIG. 27 depicts an additional embodiment of the core assembly 140 whichcan be identical to the embodiment of FIG. 26, with the addition of asecond proximal device interface 180′ in a proximal portion of the stent200, in addition to the distally located interface 180 described withreference to FIG. 26. The second interface 180′ and/or its engagementmember 182′ can be located in a proximal portion of the stent 200, e.g.,near the proximal end or in the proximal half of the stent 200. In suchan arrangement, both the interfaces 180, 180′ and/or members 182, 182′can urge the stent 200 distally in response to a distal push forceexerted on the core member 160, thereby both “pulling” the stent fromthe distal portion and “pushing” it from the proximal portion. This canalso reduce the amount of push force necessary to be exerted through thecore member 160 to advance the stent into or through the catheter 110.In addition, the interface 180′ and member 182′ when located near theproximal end of the stent 200 can facilitate re-sheathing the stent 200even when most of the stent 200 (e.g., except for the proximal-mostportion thereof) has been deployed.

In the embodiments of FIGS. 26 and 27, any of the embodiments of theproximal device interface 180 and proximal engagement member 182described herein (rotating, non-rotating, sliding, non-sliding, and anyother varieties) can be employed.

FIGS. 28 and 29 depict additional embodiments of proximal deviceinterfaces 500, 520 that may be incorporated into the core assembly 140of FIG. 26 to provide enhanced proximal re-sheathing capability.Accordingly, either of the interfaces 500, 520 can be incorporated inthe core assembly 140 in a proximal portion of the stent 200, e.g., nearthe proximal end or in the proximal half of the stent 200. The deviceinterfaces 500, 520 can be considered retraction-only interfaces in thatthey function only (or provide the option of functioning only) in aretraction or resheathing mode.

The interface 500 of FIG. 28 comprises a balloon 502 coupled to (e.g.,mounted on) the core member 160 in a proximal portion of the stent 200.The balloon 502 can be kept deflated or otherwise disengaged with thestent 200 throughout operation of the core assembly 140 until it isdesired to re-sheath the stent 200 or otherwise retract it proximallyalong the catheter 110. The balloon 502 can be inflated via an inflationlumen 504 to engage the inner surface of the stent 200, thereby grippingthe stent 200 in cooperation with the catheter 110 in a manner similarto the engagement member 182. Upon so engaging or gripping the stent200, the balloon 502 can be used to retract a partially-deployed stent200 back into the catheter 110 by pulling the core member 160proximally, in accordance with any of the re-sheathing methods describedherein. The balloon 502 can be further employed to withdraw the stent200 entirely from the catheter 110, or it can optionally be deflated andthe stent 200 can be re-deployed using the proximal engagement member182 (which has now re-engaged the retracted stent 200 so that the member182 can urge the stent 200 distally from the catheter 110 in response toa distal push force applied to the core member 160). As yet anotheroption, the balloon 502 can be kept deflated during distal advancementof the stent 200 through the catheter 110 until the distal end of thestent 200 is about to emerge from the distal end 114. At that point theballoon 502 can be inflated and both the balloon 502 and engagementmember 182 can be used to push the stent 200 distally and deploy it. Theballoon 502 can be employed to deploy the proximal portion of the stent200, e.g., before and/or after the member 182 has emerged from thecatheter 110 and become disengaged with the stent 200, while remainingavailable to re-sheath the stent 200 as described above.

The inflation lumen 504 can be incorporated into the core member 160 viaan inflation tube 506 that passes through the lumen of the tube 170 andextends to the proximal end of the core member 160 (in which case theproximal wire 168 can be replaced with a similar length of hypotube).The distal portion of the inflation tube 506 can extend past the distalend of the tube 170 into the interior of the balloon 502. There, thetube 506 can be connected to a proximal end of the distal wire 172,which extends distally therefrom.

FIG. 29 depicts another embodiment of a retraction-only proximal deviceinterface that can be incorporated in the core assembly 140 in aproximal portion of the stent 200, e.g., near the proximal end or in theproximal half of the stent 200. The interface 520 of FIG. 29 comprises aradially expanding member 522 that interacts with a wedge or cone 524 toexpand radially, and engage an inner surface of the stent 200, only whenthe core member 160 is retracted. Accordingly, the interface 520 canremain in the radially contracted, non-engaging state shown in FIG. 29(and therefore not transmit push force from the core member 160 to thestent 200) during distal advancement of the core assembly 140 and stent200. When the stent 200 has been partially deployed, and it is desiredto re-sheath the stent 200, the core member 160 can be retracted,causing the expanding member 522 to expand radially and engage thestent. The expanding member 522 thus can grip the stent 200 incooperation with the catheter 110 in a manner similar to the engagementmember 182. Upon so engaging or gripping the stent 200, the expandingmember 522 can be used to retract a partially-deployed stent 200 backinto the catheter 110 by pulling the core member 160 proximally, inaccordance with any of the re-sheathing methods described herein. Ifdesired, the expanding member 522 can be further employed to withdrawthe stent 200 entirely from the catheter 110.

FIGS. 1, 5-9 and 12 depict some embodiments and methods of use of themedical device delivery system 100. First, the catheter 110 can beinserted into the patient's vasculature via a percutaneous accesstechnique or other suitable method of access. The distal end 114 of thecatheter 110 is then advanced to a treatment site or location in theblood vessel 102, using for example any of the access routes 400. Theblood vessel 102 may comprise a vein or artery, such as an artery in abrain or within a cranium of the patient. As previously mentioned, thecatheter 110 can comprise a microcatheter. A guide catheter (not shown)can be used instead of or in addition to the catheter 110; for example,the guide catheter can first be placed in the vasculature so that itextends part or all of the way to the treatment site and a microcatheteror other catheter then inserted through the guide catheter to thetreatment site.

The treatment location may be near the aneurysm 108 formed in a wall ofthe blood vessel 102, and advancing the catheter 110 to the treatmentlocation may include advancing the distal end 114 and/or distal opening120 to a location that is distal of the aneurysm 108 (e.g., FIG. 5).Such advancement of the catheter 110 may include advancing the distalend 114 and/or distal opening 120 distally across the ostium or neck 106of the aneurysm 108, to the location in the vessel 102 distal of theaneurysm.

Once the catheter 110 has been inserted, it may extend proximally fromthe distal end 114 and/or distal opening 120 at the treatment location,through the vascular access site, to the proximal end 112 and/or hub 122which are preferably situated outside the patient's body.

After the catheter 110 has been placed, the core assembly 140 (with thestent 200 carried thereby) can be inserted, distal end first, into thelumen 116 of the catheter 110 via the hub 122 and/or proximal end 112.Where the core assembly 140 is initially at least partially containedwithin the introducer sheath 450 (FIGS. 22-25), the distal end of theintroducer sheath 450 can be inserted into the proximal end of thecatheter 110 and the core assembly 140 is advanced distally through theintroducer sheath until the distal core assembly and stent 200 exit thedistal end of the introducer sheath and pass into the lumen 116 of thecatheter 110. Such advancement of the core assembly 140 can comprisegripping the core member 160 in the proximal grip region 462 as a resultof its exposure proximal of the proximal end of the sheath 450 (and/orof the sheath 450 preventing the gripping of any other portion of thecore assembly 140). When the core assembly 140 and stent have beensufficiently advanced, the introducer sheath 450 can be retracted fromthe proximal end of the catheter 110 and/or discarded. Once the sheath450 has been so retracted/discarded, the proximal grip region 462 can beexposed for gripping proximal of the catheter proximal end 112, and theregion 462 can be the only portion of the core assembly available forgripping by the user. (Other method steps, acts or functions disclosedherein with reference to FIGS. 22-25 can also optionally be performed inconnection with the presently discussed method(s).)

The core assembly 140 and stent 200 are at this point disposed in thecatheter 110 generally as depicted in FIG. 1. In particular, the stent200 and distal portion of the core assembly 140 can be positioned in thelumen 116 of the catheter 110, with the stent 200 generally in contactwith the inner surface 118 of the catheter 110 except where the firstsection 192 a of the distal cover 192 is extending or interposedradially between the distal end 204 of the stent 200 and the innersurface 118 of the catheter 110. Further, the core member 160 can extendproximally of the proximal end 112 and/or hub 122 of the catheter 110 toa location outside of the patient's body, so that the proximal portions(e.g., proximal wire 168 where employed, and/or the proximal grip region462) of the core member 160 can be easily accessed.

Next, the core assembly 140 with the stent 200 can be axially advanceddistally within the lumen 116 of the catheter 110, toward the distal end114 of the catheter 110 and treatment location. Where the core assembly140 includes a proximal engagement member 182 and/or a distal cover 192that can rotate about the core member 160, advancing the core assembly(in this method or in any method of advancing the core member 140through a tortuous catheter, such as when such catheter is disposed in alaboratory model of vasculature) can further comprise rotating the stent200, engagement member 182 and/or distal cover 192 about the core member160. This can optionally be done without significant twisting of thecore member 160 and/or stent 200.

Where the core assembly 140 includes one or more restraints 184, 194and/or 196 having a tapered portion 250 (see FIG. 12), advancing thecore assembly 140 (in this method or in any method of advancing the coremember 140 through a tortuous catheter) can further comprise bending thecore assembly 140 and core member 160 more sharply (and/or without therestraint 184, 194 and/or 196 contacting the inner surface of the stent200) in the vessel 102 than would be possible with a non-taperedrestraint 184, 194 and/or 196 of similar axial length andcross-sectional size or diameter.

Where the core member 160 includes a tube 170 with transition zones T3B,T3A, T2 and/or T1, advancing the core assembly 140 (in this method or inany method of advancing the core member 140 through a tortuous catheter)can further comprise forming a rounded, arc-like and/or non-kinking bendin the tube 170 in one or more of such transition zones T3B, T3A, T2and/or T1, e.g., between the portions of the tube longitudinallyadjacent to the transition zone(s) being so bent.

Where the core member 160 includes a tube 170 with flex zones Z4, Z3, Z2and/or Z1, advancing the core assembly 140 (in this method or in anymethod of advancing the core member 140 through a tortuous catheter) canfurther comprise any one or combination of the following: advancing zoneZ4 into or through the cavernous ICA, the carotid siphon, the M1 segmentof the MCA, and/or the M2 segment of the MCA; advancing zone Z3 into theproximal portion of the ICA, proximal of the cavernous ICA, and/or intoor through the common carotid artery; advancing zone Z2 into or throughthe aortic arch, and/or into any of the arteries originating at the archand leading toward the neck; and/or advancing zone Z1 into the femoralartery and/or the abdominal aorta. The respective flex zone(s) canoccupy one, some or all of the foregoing anatomical regions while thestent 200 is carried by the core assembly 140 and positioned in the M1or M2 regions of the MCA, or while the intermediate portion 166 is insuch location.

Where the core assembly 140 comprises a proximal device interface 180and/or engagement member 182 positioned in a distal portion or half ofthe stent 200 (e.g., FIGS. 26-27), advancing the core assembly 140 (inthis method or in any method of advancing the core member 140 through atortuous catheter) can further comprise pulling the stent 200, or theproximal portions or proximal half thereof through the catheter 110 withthe interface 180 and/or engagement member 182. This can optionallyfurther comprise exerting less push force on the core member 160 thanwould be required in a similar delivery system that lacks a proximaldevice interface 180 and/or engagement member 182 positioned in a distalportion or half of the stent 200. Furthermore, if such a core assemblycomprises a retraction-only interface in a proximal portion or half ofthe stent 200, advancing the core assembly can comprise doing so withthe retraction-only interface disengaged from the stent.

As the stent 200 and distal cover 192 are advanced toward the distal end114 and treatment location, the first section 192 a of the distal cover192 remains extending or interposed radially between the outer surfaceand/or distal end 204 of the stent 200 and the inner surface 118 of thecatheter 110. Thus, the distal cover 192 may inhibit the distal end 204of the advancing stent 200 (e.g., the filament ends thereof) fromdamaging, abrading, or gouging the catheter 110, and from therebyimpeding progress of the stent 200 along the catheter 110. This may, inturn, avoid damage to the stent 200 such as by longitudinal compressionresulting from high friction generated between the distal end 204 of thestent 200 and the catheter 110 while distally directed force is appliedto the proximal portions of the stent 200.

Where the treatment location is near the aneurysm 108 and the distal end114 and/or distal opening 120 of the catheter 110 has been advanced to alocation that is distal of the aneurysm, advancement of the coreassembly 140 with the stent 200 toward the distal end 114 and treatmentlocation can include advancing the distal portion of the core assembly140 and the distal end 204 of the stent 200 distally through thecatheter 110 across the ostium or neck 106 of the aneurysm, to alocation in the vessel 102 distal of the aneurysm.

As the stent 200 moves closer to the distal end of the catheter 110, theuser can observe the fluorosafe marker 176 (when present) approachingthe proximal end of the catheter and thereby recognize that the stent isor will soon be close to exiting the distal end of the catheter. Havingrecognized this, the user can activate fluoroscopic imaging to view theexit of the stent from the distal catheter end via such imaging, andthen proceed to urge the core assembly distally and thereby cause thestent to exit the distal end of the catheter.

To begin expansion of the stent 200 (see FIGS. 5-9), the core assembly140 may be held stationary and the catheter 110 may be withdrawnproximally over the stent 200 and distal portion of the core assembly140, as shown in FIGS. 6-7. (Optionally, the core assembly and stent canbe advanced distally while performing this step, instead of or inaddition to withdrawal of the catheter.) Where the core assembly 140comprises a selectively activatable interface such as the balloon 502(FIG. 28) in a proximal portion or half of the stent 200, the interfacecan now be activated (e.g., the balloon now inflated and thereby changedfrom a deflated, disengaged condition to an inflated condition in whichit engages the inner wall of the stent) to assist in urging the stentout of the catheter 110. In any event, as a result, the stent 200(except for any portion retained within the catheter 110) can bereleased and permitted to expand into engagement with the inner wall ofthe blood vessel 102, as shown in FIGS. 6-7. Some embodiments of thestent 200 (such as certain braided stents) can shorten axially whileexpanding radially. As a result of (i) any axial foreshortening of thestent 200, (ii) radial expansion of the stent 200, and/or (iii) radialexpansion of the distal cover 192 in response to radial expansion of thestent 200, the strips or tube portions of the first section 192 a of thedistal cover 192 can disengage from contact with the distal end 204 ofthe stent 200, while in some embodiments separating and moving radiallyoutward as well.

As the distal portion of the stent 200 expands, it can cause the distalcover 192 to be opened or moved from the first orientation. When thestent 200 can foreshorten as it expands, the stent 200 can withdraw fromengagement with the distal cover 192, as shown in FIG. 6. After thedistal cover 192 has become disengaged from the stent 200 to reach thestate shown in FIG. 6, the cover can proceed to the second orientationas shown in FIG. 7, as oncoming blood flow and/or other forces urge thefirst section 192 a distally. Alternatively, the distal cover 192 canremain substantially in the disengaged, proximally-extendingconfiguration shown in FIG. 6 until the core assembly 140 is withdrawnproximally into the catheter 110, at which point the distal end 114 ofthe catheter 110 can force the approaching first section 192 a of thecover 192 to evert or otherwise take on the second configuration asshown in FIGS. 7-8.

In some embodiments, as the distal cover 192 disengages from the stent,it no longer covers the distal end 204 of the stent 200; instead, itsfirst section 192 a is now spaced distally from the stent distal end 204as shown in FIG. 6. In this state, the strips or tube portions formingthe first section 192 a can be free or unconfined within the lumen ofthe blood vessel 102. As similarly noted above, the strips or tubeportions can have free first ends, as well as second ends that arecoupled to the core assembly 140. The free first ends can cover at leasta portion of the stent distal portion during delivery of the stent.Further, when the stent is expanded and/or the core assembly 140 isproximally withdrawn into the catheter, the strips or tube portions canbe everted, such that free first ends of the strips, wings, or elongateportions are drawn together distal to the second ends thereof.

The pullback of the catheter 110 (and/or distal movement of the coreassembly 140) and expansion of the stent 200 may be done in multiplediscrete steps. For example, the catheter 110 may initially be pulledback proximally only part of the way as shown in FIGS. 6-17, and onlythe distal portion 204 of the stent 200 expanded into engagement withthe vessel wall. Such initial partial expansion facilitates anchoringthe distal portion of the stent in the vessel 102, which in turnfacilitates longitudinal stretching or compression of the stent 200 asdesired by the clinician during or prior to expansion of the remainingportions of the stent 200 into the vessel 102. Initial partial expansioncan also facilitate confirmation by the clinician that the distalportion of the stent 200 has “landed” in the desired location in thevessel 102 (e.g., distal of the neck or ostium of any aneurysm formed inthe vessel wall) prior to expansion of the remaining portions of thestent 200. Generally, where an aneurysm is present in the vessel 102,proper placement of the stent 200 can include positioning a distalportion of the stent 200 in the vessel lumen distal of the aneurysm neck106 and a proximal portion of the stent in the vessel lumen proximal ofthe aneurysm neck 106, such that the stent 200 extends across the neck(FIG. 9). Where the expanded stent 200 is appropriately configured, itmay then perform a therapeutic flow-diverting function with respect tothe aneurysm 108.

While the delivery system 100 is in the configuration shown in FIG. 6 or7, with the proximal end 202 of the stent 200 retained within thecatheter 110 between the proximal engagement member 182 and the innerwall 118 of the catheter, the partially expanded stent 200 can beresheathed or retracted proximally into the catheter 110 as shown inFIG. 8. The engagement member 182 and catheter 110 can secure, grip, orengage the stent 200 to a sufficient degree to permit the catheter 110to be advanced distally over the partially expanded stent 200 (and/orthe core member 160 withdrawn proximally relative to the catheter 110)until the stent 200 is again positioned in the lumen 116 of the catheter110. Thus, the engagement member 182 can exert a proximal force on thestent 200 as the stent 200 is withdrawn or retracted into the catheter110. Where the core assembly includes a retraction-only interface in aproximal half or portion of the stent (e.g., FIGS. 28-29), theretraction-only interface can be activated and employed to retract thestent proximally into the catheter 110. Thus, the retraction-onlyinterface can exert a proximal force on the stent 200 as the stent 200is withdrawn or retracted into the catheter 110.

FIGS. 6-7 also show a first aspect of a process of resheathing the stent200, during or prior to the stent 204 being drawn into the lumen 116 ofthe catheter 110. Because the previously stent-engaging portion (e.g.,the first section 192 a) of the distal cover 192 has moved radiallyoutward from the core member 160 (e.g., FIG. 6) and/or distally relativeto the core member 160 (e.g., FIG. 7), it does not impede the entranceof the distal portion and distal end 204 of the stent 200 into thedistal opening 120 of the catheter 110 (e.g., to get to the state shownin FIG. 8) during resheathing. Accordingly, the resheathing process cancomprise moving the stent 200 (including the distal end 204) into thecatheter 110 through the distal opening 120 while the previouslystent-engaging portion (e.g., the first section 192 a) of the distalcover 192 is in a second, everted, or resheathing configuration in whichthe stent-engaging portion is disposed radially outward from the coremember 160 and/or the first section 192 a of the distal cover 192 isdisposed distally relative to the core member 160, the second section192 b, and/or the distal tip 165, in comparison to a first,encapsulating, or delivery configuration (e.g., FIG. 1, 3) of thestent-engaging portion (e.g., the first section 192 a) of the distalcover 192.

FIG. 8 shows a second aspect of the resheathing process currently underdiscussion. In this aspect of the process, the core assembly 140 can bemoved further proximally into the catheter 110 (and/or the catheter 110is moved further distally over the core assembly 140) until the distalcover 192 enters the catheter 110 via the distal opening 120. As notedabove, the first section 192 a of the distal cover 192 is preferablysufficiently flexible to evert and thereby attain the second, everted,or resheathing configuration shown in FIGS. 7-8. In the second, everted,or resheathing configuration, the first section 192 a of the distalcover 192 can extend generally in a distal direction, away from thestent 200, and/or extend distally of the second section 192 b of thedistal cover 192. Further, in some embodiments, the first section 192 aof the distal cover 192 can also radially overlap the distal tip 165and/or the distal restraint 196. Instead of or in addition to theseaspects of the second, everted, or resheathing configuration, the distalcover 192 can be radially small enough to extend into the lumen 116 ofthe catheter 110, either partially or wholly as shown in FIG. 8, and/orthe entire distal cover 192 can be spaced distally from the distal end204 of the stent 200 in the lumen 116 of the catheter 110.

Accordingly, in accordance with some embodiments of methods disclosedherein, when operating the delivery system 100, a clinician can checkthe initial partial expansion of the stent 200 (e.g., as shown in FIGS.6-7) and, if the initial placement is unsatisfactory or if the initialexpansion of the stent 200 is unsatisfactory, the clinician canrecapture, collapse, withdraw, or resheath the stent 200 into thecatheter 110, as described above with respect to FIGS. 6-8. Afterresheathing, the clinician can attempt to deploy the stent again, asdescribed herein, beginning for example with the state depicted in FIG.8, and resulting for example, in the state depicted in FIG. 6-7 or 9.Resheathing can also be performed, and the delivery system 100 and stent200 removed from the patient entirely, if for example, the deliveryand/or expansion of the stent 200 damages or reveals a defect in, orimproper sizing of, the stent 200 or delivery system 100. After aninitial partial expansion of the stent 200, the depicted core assembly140 can optionally be entirely removed with the stent 200 from thecatheter 110 without need to remove the catheter 110 from the bloodvessel 102. In this manner, access to the treatment site in the bloodvessel 102 can be maintained via the catheter 110 and, if desired,additional attempts to deliver the stent 200 can be made through thecatheter 110.

If the initial expansion of the stent 200 in the vessel 102 issatisfactory, full deployment and expansion can be completed to resultin the state depicted in FIG. 9. The proximal end 202 of the stent 200may be released from the catheter 110 by holding the core member 160stationary and withdrawing the catheter proximally relative to the coremember 160 and the stent 200 until the distal opening 120 is proximal ofthe proximal end 202 of the stent 200. No longer constrained by thecatheter 110, the proximal end 202 of the stent 200 can now expand intocontact with the wall of the vessel 102, as shown FIG. 9. (Note thatuntil this point, according to an aspect of some embodiments, thepartially expanded stent 200 had been fully resheathable.) The fullydeployed stent 200 extends across the neck 106 of the aneurysm 108, andcan optionally perform a therapeutic flow-diverting function withrespect to the aneurysm.

Following full expansion of the stent 200, the core assembly 140 can bedrawn back into the catheter 110. Both the catheter 110 and coreassembly 140 can be withdrawn from the patient, either simultaneously orsequentially. However, when the stent has been successfully released,the core assembly 140 can also be entirely removed from the catheter110, with the catheter 110 remaining in place, and a second coreassembly can be inserted into the catheter lumen. The second coreassembly can be configured to deliver a second stent to the treatmentsite in order to perform, e.g., a telescoping procedure.

In the present disclosure, numerous references are made to moving thecatheter 110 axially over the core assembly 140, and moving the coreassembly 140 axially within the catheter 110. Except where specificallynoted to the contrary, all such references to one form of this relativemovement should be understood to include the other as an alternative.

Information regarding additional embodiments of the medical devicedelivery system 100, and additional details, components and methods thatcan optionally be used or implemented in or with the embodiments of thedelivery system 100 described herein, can be found in U.S. patentapplication Ser. No. 13/664,547, filed on Oct. 31, 2012, titled METHODSAND APPARATUS FOR LUMINAL STENTING, the entirety of which is herebyincorporated by reference herein and made a part of this specification.The delivery system 100 and methods disclosed herein can optionally besimilar to any of the delivery systems or methods disclosed in theabove-incorporated application, except as further described herein.

The apparatus and methods discussed herein are not limited to thedeployment and use of a medical device or stent within the vascularsystem but may include any number of further treatment applications.Other treatment sites may include areas or regions of the body includingany hollow anatomical structures.

Although the detailed description contains many specifics, these shouldnot be construed as limiting the scope of the subject technology butmerely as illustrating different examples and aspects of the subjecttechnology. It should be appreciated that the scope of the subjecttechnology includes other embodiments not discussed in detail above.Various other modifications, changes and variations may be made in thearrangement, operation and details of the method and apparatus of thesubject technology disclosed herein without departing from the scope ofthe present disclosure. Unless otherwise expressed, reference to anelement in the singular is not intended to mean “one and only one”unless explicitly stated, but rather is meant to mean “one or more.” Inaddition, it is not necessary for a device or method to address everyproblem that is solvable (or possess every advantage that is achievable)by different embodiments of the disclosure in order to be encompassedwithin the scope of the disclosure. The use herein of “can” andderivatives thereof shall be understood in the sense of “possibly” or“optionally” as opposed to an affirmative capability.

We claim:
 1. A stent delivery system, comprising: a core member havingan intermediate portion and an elongate, spiral-cut tube extendingproximally of the intermediate portion, the tube having first and secondflex zones, the second flex zone being proximal of the first flex zone,and a transition zone between the first and second flex zones; the firstflex zone having a bending stiffness of less than 120 N*mmA2 so as to benavigable to the common carotid artery, the spiral cut of the tube inthe first flex zone having a first pitch, the second flex zone having abending stiffness of greater than 180 N*mmA2, the spiral cut of the tubein the second flex zone having a second pitch different from the firstpitch wherein the spiral cut of the tube in the transition zone changesfrom the first pitch to the second pitch in a series of pitchtransitions, the pitch in the transition zone increasing by an overallpercent increase from the first pitch to the second pitch, such that theaverage overall percent increase achieved per transition is 10% or less;and a stent carried by the intermediate portion.
 2. The system of claim1, wherein the pitch transitions of the spiral cut of the tube have adensity along the transition zone greater than 0.5 transitions percentimeter.
 3. The system of claim 1, wherein the pitch of the spiralcut of the tube increases by over 80% from the first pitch to the secondpitch in a proximal direction in the transition zone.
 4. The system ofclaim 1, wherein the first flex zone has a length that is greater than50 mm.
 5. The system of claim 1, wherein the second flex zone has alength that is greater than 200 mm.
 6. The system of claim 1, whereinthe second flex zone bending stiffness is 190-210 N*mm{circumflex over( )}2.
 7. The system of claim 1, wherein the transition zone comprisesabout 10 pitch transitions.
 8. The system of claim 1, wherein a distalend of the first flex zone is spaced 300-340 mm from a proximal end ofthe stent.
 9. The system of claim 8, wherein a distal end of the secondflex zone is spaced 480-540 mm from the proximal end of the stent. 10.The system of claim 1, wherein the spiral cut of the tube prevails alonga cut length of the tube, the cut length being greater than 50 cm. 11.The system of claim 10, wherein the spiral cut is contiguous along thecut length.
 12. The system of claim 10, further comprising a polymericouter layer disposed over an outer surface of the tube along at least aportion of the cut length, wherein the spiral cut is not cut into thepolymeric outer layer.
 13. The system of claim 12, wherein the polymericouter layer covers the cut length of the tube.
 14. A stent deliverysystem, comprising: a core member having an intermediate portion and anelongate, spiral-cut tube extending proximally of the intermediateportion, the tube having first, second, and third flex zones and firstand second transition zones, the first transition zone between the firstand second flex zones, the second transition zone between the second andthird flex zones, the core member being configured such that (i) abending stiffness of the first flex zone is greater than a bendingstiffness of the second flex zone and a bending stiffness of the thirdflex zone and (ii) the bending stiffness of the second flex zone isgreater than the bending stiffness of the third flex zone, for providingdistal pushability of portions of the core member distal to the firstflex zone, the spiral cut of the tube has (i) a first pitch in the firstflex zone, (ii) a second pitch in the second flex zone, the first pitchbeing at least 35% greater than the second pitch, (iii) a third pitch inthe third flex zone, and (iv) changing in the first transition zone fromthe first pitch to the second pitch in a series of pitch transitionshaving a pitch transition density of greater than 1 transition percentimeter, and (v) in the second transition zone from the second pitchto the third pitch in a series of pitch transitions for preventingbuckling of the tube in the first and second transition zones when thetube is pushed; and a stent carried by the intermediate portion.
 15. Thesystem of claim 14, wherein the tube comprises an uncut segment at adistal portion of the tube.
 16. The system of claim 14, wherein thespiral cut of the tube prevails along a cut length of the tube, the cutlength being greater than 50 cm.
 17. The system of claim 16, wherein thespiral cut is contiguous along the cut length.
 18. The system of claim17, further comprising a polymeric outer layer disposed over an outersurface of the tube along at least a portion of the cut length, whereinthe spiral cut is not cut into the polymeric outer layer.
 19. The systemof claim 18, wherein the polymeric outer layer covers the cut length ofthe tube.